Answer:
B. fast-twitch fibers can deliver a quick burst of power. Slow-twitch fibers can maintain a contraction for a longer time.
Answer:
the person above is right, just came for answers lol :')
Explanation:
A 80-kg person stands at rest on a scale while pulling vertically downwards on a rope that is above them. Use g = 9.80 m/s2.
With what magnitude force must the tension in the rope be pulling on the person so that the scale reads 25% of the persons weight?
Answer:
The tension in the rope is 588 N
Explanation:
I have attached a free body diagram of the problem.
First we calculate the force applied downwards by the person's weight:
[tex]F_{weight} =m*a = 80 kg * 9.8 \frac{m}{s^{2}} = 784 N[/tex]
If the scale reads a 25% of the person' weight:
[tex]F_{Scale} = F_{weight}*0.25=784N*0.25=196N[/tex]
which is the same value (but opposite) to the effective weight of the persons ([tex]F_{Person}=-F_{Scale}[/tex])
The other 75% of the total weight is the force of the rope pulling the person upwards.
[tex]F_{Pull}= F_{weight}*0.75=784N*0.75=588N[/tex]
To verify, we can use 1st Newton's law
∑F = 0
[tex]F_{Rope}-F_{Pull}+F_{Person}-F_{Scale}=0 \\588N-588N+196N-196N=0[/tex]
1. a. Describe the type of energy that is observed when a musician's finger plucks a guitar string. does it give your ear kenetic or potential energy .
Answer:
kinetic
Explanation:
Answer:
kinetic energy.
Explanation:
differentiate between speed and velocity
Explanation:
Speed - The rate at which something moves
Velocity - The speed of something in a specific direction
Velocity is kind of a specific type of speed.
Question 2: If a runner travels 50 m in 5 s, his acceleration is
1 point
250 m/s/s
50 m/s/s
10 m/s/s
2 m/s/s
A tired worker pushes a heavy (100-kg) crate that is resting on a thick pile carpet. The coefficients of static and kinetic friction are 0.6 and 0.4, respectively. The worker pushes with a horizontal force of 490 N. The frictional force exerted by the surface is
Answer:
The friction force exerted by the surface is 490 newtons.
Explanation:
From Physics, we remember that static friction force ([tex]f_{s}[/tex]), measured in newtons, for a particle on a horizontal surface is represented by the following inequation:
[tex]f_{s} \leq \mu_{s}\cdot m \cdot g[/tex] (Eq. 1)
Where:
[tex]\mu_{s}[/tex] - Static coefficient of friction, dimensionless.
[tex]m[/tex] - Mass of the crate, measured in kilograms.
[tex]g[/tex] - Gravitational acceleration, measured in meters per square second.
If [tex]f_{s} = \mu_{s}\cdot m \cdot g[/tex], then crate will experiment an imminent motion. The maximum static friction force is: ([tex]\mu_{s} = 0.6[/tex], [tex]m = 100\,kg[/tex], [tex]g = 9.807\,\frac{m}{s^{2}}[/tex])
[tex]f_{s} = (0.6)\cdot (100\,kg)\cdot \left(9.807\,\frac{m}{s^{2}} \right)[/tex]
[tex]f_{s} = 588.42\,N[/tex]
From Newton's Laws we get that current force of friction as reaction to the pulling force done by the worker on the crate is:
[tex]\Sigma F = F-f = 0[/tex]
[tex]f = F[/tex] (Eq. 2)
Where:
[tex]F[/tex] - Horizontal force done by the worker, measured in newtons.
[tex]f[/tex] - Static friction force, measured in newtons.
If [tex]F = 490\,N[/tex], then the static friction force exerted by the surface is:
[tex]f = 490\,N[/tex]
Given that [tex]f < f_{s}[/tex], the crate does not change its state of motion. The friction force exerted by the surface is 490 newtons.
will give brainliest pls help
Answer:
a and c
Explanation:
4. A 5.0 kg block moving to the right at 12.0 m/sec collides with a 4.0 kg block moving to the right at 2 m/sec. If the 4.0 kg moves to the right at 10 m/sec after the collision, what will be the speed of the 5.0 kg block? How much energy was lost during the collision?
Answer:
Energy lost = 55.28Joules
Explanation:
Using the law of momentum:
m1u1+m2u2 = m1v1+m2v2
m1 and m2 are the masses of the objects
u1 and u2 are the initial velocities.
v1 and v2 are final velocities
Given
m1 = 5kg
m2 = 4kg
u1 = 12m/s
u2 = 2m/s
v1 = 10m/s
v2 = ?
Substitute
5(12)+4(2)=4(10)+5v2
60+8 = 40+5v2
68-40 = 5v2
28 = 5v2
v2 = 28/5
v2 = 5.6m/sec
Hence the speed of the 5kg block is 5.6m/s
Energy lost = Kinetic energy after collision - kinetic energy before collision
KE after collision = 1/2m1v1²+1/2m2v2²
KE after collision = 1/2(5)10²+1/2(4)(5.6)²
= 250+62.72
= 312.72Joules
KE before collision = 1/2m1u1²+1/2m2u2²
KE before collision = 1/2(5)12²+1/2(4)(2)²
= 360+8
= 368Joules
Energy lost = 368-312.72
Energy lost = 55.28Joules
A race car accelerates from rest with a displacement of 25.0 m. If the
acceleration is 1.2 m/s2, what is the car's final velocity?
Answer:
Vf = Vi + at
t = Vf - Vi = 0.0m/s - 1.75 m/s
--------- = ------------------------- = 8.8s
a -0.20 m/s(squared)
Explanation:
This is what I got I am pretty sure it's correct but correct me if I'm wrong : )
The speed of a 4.0-N hockey puck, sliding across a level ice surface, decreases at the rate of 2 m/s 2. The coefficient of kinetic friction between the puck and ice is:
Answer:
μ = 0.2041
Explanation:
Given
[tex]a = -2m/s^2[/tex]
Required
Determine the coefficient of friction (μ)
The acceleration is negative because it is decreasing.
Solving further, we have that:
[tex]F_f =[/tex] μmg
Where
μ = Coefficient of kinetic friction
[tex]F_f = ma[/tex]
So, we have:
ma = μmg
Divide both sides by m
a = μg
Substitute values for a and g
2 = μ * 9.8
Solve for μ
μ = 2/9.8
μ = 0.2041
Calculate the translational speed of a cylinder when it reaches the foot of an incline 7.30 mm high. Assume it starts from rest and rolls without slipping.
Answer:
9.77 m/s
Explanation:
Since the cylinder is rolling, it will have both translational and rotational kinetic energy.
From conservation of energy, its initial mechanical energy equals its final mechanical energy.
So, K' + U' = K + U where K and U are the initial kinetic and potential energies respectively and K' and U' are the final kinetic and potential energies respectively.
So, Since the cylinder starts from rest, its initial kinetic energy K = 0, its initial potential energy = mgh where m = mass of cylinder, g = acceleration due to gravity = 9.8 m/s² and h = height of incline = 7.30 mm = 7.3 × 10⁻³ m . Its final kinetic energy K' = 1/2Iω² + 1/2mv² where I = moment of inertia of cylinder = 1/2mr² where r = radius of cylinder and v = translational velocity of cylinder. Its final potential energy U' = 0. Substituting these into the equation, we have
K' + U' = K + U
1/2Iω² + 1/2mv² + 0 = 0 + mgh
1/2(1/2mr²)ω² + 1/2mv² = mgh
1/4mr²ω² + 1/2mv² = mgh
1/4m(rω)² + 1/2mv² = mgh v = rω
1/4mv² + 1/2mv² = mgh
3/4mv² = mgh
v² = 4gh/3
v = √(4gh/3)
v = √(4 × 9.8 m/s² × 7.3 × 10⁻³ m/3)
v = (√286.16/3) m/s
v = (√95.39) m/s
v = 9.77 m/s
9. A 50 kg halfback is in the process of making a turn on a football field.
The halfback makes 1/4 of a turn with a radius of 15 meters in 2.1 seconds
before being tackled. What is the net force acting on the halfback before
he is tackled?
Answer:
Net force = 419.5N
Explanation:
Given the following data;
Mass = 50kg
Radius = 15m
Time = 2.1 secs
Turns = 1/4 = 0.25
In order to find the net force, we would first of all solve for the speed and acceleration of the halfback.
To find speed;
Speed can be defined as distance covered per unit time. Speed is a scalar quantity and as such it has magnitude but no direction.
Mathematically, speed is given by the equation;
[tex]Speed = \frac{distance}{time}[/tex]
But the distance traveled is given by the circumference of a circle = [tex] 2\pi r[/tex]
Since he covered 1/4th of a turn;
[tex] Distance = 0.25 * 2 \pi *r[/tex]
Substituting into the equation;
[tex] Speed, v = \frac {(0.25*2*3.142 * 15)}{2.1}[/tex]
[tex] Speed, v = \frac {23.565}{2.1}[/tex]
Speed, v = 11.22m/s
To find acceleration;
[tex] Acceleration, a = \frac {v^{2}}{r}[/tex]
Where, v = 11.22m/s and r = 15m
Substituting into the equation, we have;
[tex] Acceleration, a = \frac {11.22^{2}}{15}[/tex]
[tex] Acceleration, a = \frac {125.8884}{15}[/tex]
Acceleration, a = 8.39m/s²
To find the net force;
Force is given by the multiplication of mass and acceleration.
Mathematically, Force is;
[tex] F = ma[/tex]
Where;
F represents force.m represents the mass of an object.a represents acceleration.Substituting into the equation, we have;
[tex] F = 50 * 8.39[/tex]
F = 419.5N
Therefore, the net force acting upon the halfback is 419.5 Newton.
A Ferris wheel rotates at an angular velocity of 0.25 rad/s. Starting from rest, it reaches its operating speed with an average angular acceleration of 0.027 rad/s2. How long does it take the wheel to come up to operating speed?
Answer:
t = 9.25 s
Explanation:
Given that,
Initial angular velocity, [tex]\omega_o=0[/tex] (at rest)
Final angular velocity, [tex]\omega_o=0.25\ rad/s[/tex]
Angular acceleration, [tex]\alpha =0.027\ rad/s^2[/tex]
We need to find the time it take the wheel to come up to operating speed. We know that the angular acceleration in terms of angular speed is given by :
[tex]\alpha =\dfrac{\omega_f-\omega_o}{t}\\\\t=\dfrac{\omega_f-\omega_o}{\alpha }\\\\t=\dfrac{0.25-0}{0.027}\\\\t=9.25\ s[/tex]
So, it will reach up to the operating speed in 9.25 s.
A roller coaster stops at the top of a hill. What force brings the roller coaster back down to the ground?
Answer:
Simple enough that it seems like a trick question: gravity.
Explain the differences between getting burned by fire and getting burned by dry ice?
Need it ASAP
What type of energy is possessed by a pear falling from a tree,
just before it touches the ground?
zero energy
kinetic energy
potential energy
kinetic and potential energy
Answer:
Kinetic Energy
Explanation:
I can't really explain it, but that's the correct answer.
A disk rotates about its central axis starting from rest and accelerates with constant angular acceleration. At one time it is rotating at 4.40 rev/s; 60.0 revolutions later, its angular speed is 15.0 rev/s. Calculate (a) the angular acceleration (rev/s2), (b) the time required to complete the 60.0 revolutions, (c) the time required to reach the 4.40 rev/s angular speed, and (d) the number of revolutions from rest until the time the disk reaches the 4.40 rev/s angular speed.
Answer:
The answer is below
Explanation:
a) Using the formula:
[tex]\omega^2=\omega_o^2+2\alpha \theta\\\\\omega=final\ velocity=15\ rev/s,w_o=initial\ velocity=4.4\ rev/s, \\\theta=distance=60\ rev\\\\Substituting:\\\\15^2=4.4^2+2(60)\alpha\\\\2(60)\alpha=15^2-4.4^2\\\\2(60)\alpha=205.64\\\\\alpha=1.71\ rev/s^2[/tex]
b) The disk is initially at rest. Using the formula:
[tex]\theta=\omega_ot+\frac{1}{2}\alpha t^2 \\\\but\ \omega_o=0(rest), \theta=60\ rev,\alpha=1.71\ rev/s^2\\\\Subsituting:\\\\60=0+\frac{1}{2}(1.71) t^2\\\\t=8.4\ s[/tex]
c)
[tex]\omega=\omega_o+\alpha t \\\\but\ \omega_o=0(rest), \omega=4.4 \ rev/s\ rev,\alpha=1.71\ rev/s^2\\\\Subsituting:\\\\4.4=1.71t\\\\t=2.6\ s[/tex]
d)
[tex]\omega^2=\omega_o^2+2\alpha \theta\\\\\omega=final\ velocity=4.4\ rev/s,w_o=initial\ velocity=0\ rev/s, \\\alpha=1.71\ rev/s^2\\\\Substituting:\\\\4.4^2=0+2(1.71)\theta\\\\19.36=3.42\theta\\\\\theta=5.66\ rev[/tex]
A dentist’s drill starts from rest. After 7.28 s of constant angular acceleration it turns at a rate of 16740 rev/min. Find the drill’s angular acceleration. Answer in units of rad/s 2 .
Answer:
[tex]\alpha =240.79\ rad/s^2[/tex]
Explanation:
Given that,
Initial angular velocity, [tex]\omega_i=0[/tex]
Final angular velocity, [tex]\omega_f=16740\ rev/min = 1753\ rad/s[/tex]
We need to find the angular acceleration of the drill. It is given by the formula as follows :
[tex]\alpha =\dfrac{\omega_f-\omega_i}{t}\\\\\alpha =\dfrac{1753-0}{7.28}\\\\\alpha =240.79\ rad/s^2[/tex]
So, the angular acceleration of the drill is [tex]240.79\ rad/s^2[/tex].
What is centripetal force?Define it with example.
Answer:
Centripetal force is defined as, "the force that is necessary to keep an object moving in a curved path and that is directed inward toward the center of rotation,"
Explanation:
so if you put a small ball por grape and put it on a table and you take a wine glass and spin it around the grape the grape will continue spinning even if you stop spinning the glass hope this helped
;)
Answer:
A force acting on a moving body at an angle to the direction of motion, tending to make the body follow a circular or curved path. The force of gravity acting on a satellite in orbit is an example of a centripetal force; the friction of the tires of a car making a turn similarly provides centripetal force on the car.
Explanation:
A particle starts from rest and is acted on by a net force that does work at a rate that is proportional to the time t. The speed of the particle is proportional to:_____
a. √t
b. t
c. t^2
d.1/√t
e. 1/t
Answer:
The speed of the particle is proportional to:
c. t²
Explanation:
Given;
initial velocity of the particle, u = 0
let the net force on the object = F
Work done on the particle is given by;
W = F x d
W ∝ t
[tex]Fd \ \alpha \ t\\\\\frac{mv}{t}d \ \ \alpha \ t\\\\mvd \ \ \alpha \ t^2\\\\v \ \ \alpha \ t^2[/tex]
Therefore, the speed of the particle is proportional to t²
The speed of the particle is proportional to t.
It should be noted that work is a change in kinetic energy. Therefore, power will be calculated as:
Power = Work / Time = force × velocity
Power is proportional to t. Since force is a constant, then the velocity will be proportional to t. Therefore, the speed of the particle is proportional to t.
Read related link on:
https://brainly.com/question/18276129
A 3.00-kg block starts from rest at the top of a 35.5° incline and slides 2.00 m down the incline in 1.45 s. (a) Find the acceleration of the block.
Answer:
0.344 m/s^2
Explanation:
The first step is to calculate V
V= distance /time
= 2/1.45
= 1.379 m/s
Therefore the acceleration of the block can be calculated as follows
a= V - U/2d
= 1.379 - 0/2×2
= 1.379/4
= 0.344 m/s^2
A pair of equal-length vectors at right angles to each other have a resultant. If the angle between the vectors is less than 90°, their resultant is
Answer:
Larger in magnitude
Explanation:
As the vectors get closer reducing the 90 degree angle, based on the "parallelogram rule" for vector addition, the magnitude of the resultant vector gets larger than when they are forming a 90 degree angle.
How much force (in N) is exerted on one side of an 35.3 cm by 50.0 cm sheet of paper by the atmosphere
Answer:
A force of 1.788 newtons is exerted on one side of the sheet of paper by the atmosphere.
Explanation:
From definition of pressure, we get that force exerted by the atmosphere ([tex]F[/tex]), measured in newtons, on one side of the sheet of paper is given by the expression:
[tex]F = P_{atm}\cdot w\cdot l[/tex] (Eq. 1)
Where:
[tex]P_{atm}[/tex] - Atmospheric pressure, measured in pascals.
[tex]w[/tex] - Width of the sheet of paper, measured in meters.
[tex]l[/tex] - Length of the sheet of paper, measured in meters.
If we know that [tex]P_{atm} = 101325\,Pa[/tex], [tex]w = 0.353\,m[/tex] and [tex]l = 0.05\,m[/tex], then the force exerted on one side of the sheet of paper is:
[tex]F = (101325\,Pa)\cdot (0.353\,m)\cdot (0.05\,m)[/tex]
[tex]F = 1.788\,N[/tex]
A force of 1.788 newtons is exerted on one side of the sheet of paper by the atmosphere.
State two function of the mass M placed on the metre rule
correct answer is mass media is correct answer OK
1.A large beach ball weighs 4.0 N. One person pushes it with a force of 7.0 N due South while another person pushes it 5.0 N due East. Find the acceleration on the beach ball.
2. What is the weight of a 70 kg astronaut on the earth, on the moon, (g=1.6 m/s2), on Venus (g = 18.7 m/s2) and in outer space traveling at a constant velocity
Answer:
1. force applied southward = -4 j
force applied eastward = 5 i
total force applied = 5i - 4j
magnitude of total force applied = √(5)²+(-4)²
magnitude of total force applied = √25 + 16 = √41
magnitude of total force applied = 6.4N
But the beach ball also weighs 4 N,
which means that a force of 4N is required to overcome the inertia of the ball
Net force applied on the ball = total force applied - force applied by inertia
Net force applied on the ball = 6.4 - 4
Net force applied on the ball = 2.4 N
Mass of the ball:
Mass of the ball = weight of the ball / gravitational constant
Mass of the ball = 4 / 9.8 = 0.4 kg
Acceleration of Ball:
from newton's second law of motion:
F = ma
replacing the variables
2.4 = 0.4 * a (where a is the acceleration of the ball)
a = 2.4/0.4
a = 6 m/s²
2. Mass of astronaut = 70 kg
Weight of Earth:
Weight = Mass * acceleration due to gravity
Weight = 70 * 9.8
Weight = 686 N
Weight on Moon:
Weight = Mass * acceleration due to gravity
Weight = 70 * 1.6 (we are given that g = 1.6 on moon)
Weight = 112 N
Weight on Venus:
Weight = Mass * acceleration due to gravity
Weight = 70 * 18.7 (we are given that g = 18.7 on Venus)
Weight = 1309 N
An Indy 500 race car's velocity increases from 2 mis to 40 mis over a 40 s time interval. What is its
acceleration ?
Answer:8
Explanation:
A student throws a water bottle upward into the air. It takes 1.2 seconds for the bottle to reach it's
maximum height. How much time will it take for the water bottle to return to the student's hand
(from its maximum height)?
Answer:
1.2 seconds
Explanation:
Formula for total time of flight in projectile is; T = 2u/g
Now, for the time to reach maximum height, it is gotten from Newton's first equation of motion;
v = u + gt
t is time taken to reach maximum height.
But in this case, g will be negative since motion is against gravity. Final velocity will be 0 m/s at max height.
Thus;
0 = u - gt
u = gt
t = u/g
Putting t for u/g in the equation of total time of flight, we have;
T = 2t
We are given t = 1.2
Thus, T = 2 × 1.2 = 2.4
Since total time of flight is 2.4 s and time to get to maximum height is 1.2 s, then it means time to fall from maximum height back to the students hand is; 2.4 - 1.2 = 1.2 s
Help pleaseeeee!
If a force of 12 N is applied to a 4.0 kg object, what acceleration is produced?
Answer:
The answer is 3 m/s²Explanation:
The acceleration of an object given it's mass and the force acting on it can be found by using the formula
[tex]a = \frac{f}{m} \\ [/tex]
where
f is the force
m is the mass
From the question we have
[tex]a = \frac{12}{4} \\ [/tex]
We have the final answer as
3 m/s²Hope this helps you
A 1500 kg car hits a haystack at 8m/s and comes to a stop after 0.6 seconds
A)what is the change in momentum of the car ?
B) what is the impulse that acts on the car ?
C) what is the average force that acts on the car during the collision?
D) what is the work done by the haystack in stopping the car ?
Answer:
Kindly check explanation
Explanation:
Change in momentum:
m(v - u)
M = mass = 1500kg
v = final velocity = 0 m/s
u = initial velocity = 8m/s
Momentum = 1500(8 - 0)
Momentum = 1500 * 8
Momentum = 12000 kgm/s
B.) impulse that acts on the car
Impulse = Force * time
Impulse = change in momentum with time
Impulse = m(v - u)
Hence, impulse = 12000Ns
C.) Average force action on the car during collision
Impulse = Force * time
12000 = force * 0.6
12000/ 0.6 = force
Force = 20000 N
D.) Workdone by haystack in stopping the car :
Workdone = Force * Distance
Distance = speed * time
Distance = 8 * 0.6
Distance = 4.8m
Hence,
Workdone = 20,000 * 4.8 = 96000 J
How much is the spring stretched, in meters, by an object with a mass of 0.49 kg that is hanging from the spring at rest
Answer:
1.6m
Explanation:
Using the spring equation, which is as follows:
F = Kx
Where; F = force applied on the spring (N)
K = spring constant (3kg/s²)
x = extension of spring (m)
However, Force applied by object = mass × acceleration (9.8m/s²)
F = 0.49kg × 9.8m/s²
F = 4.802N
Since, F = 4.802N
F = Kx
4.802 = 3 × x
4.802 = 3x
x = 4.802/3
x = 1.6006
x = 1.6m
The spring is stretched i.e. the extension of the spring, by 1.6m
When an unknown resistance RxRx is placed in a Wheatstone bridge, it is possible to balance the bridge by adjusting R3R3 to be 2500ΩΩ. What is RxRx if R2R1=0.625R2R1=0.625?
Answer:
Rₓ = 1562.5 Ω
Explanation:
The formula for the wheat stone bridge in balanced condition is given as follows:
R₁/R₂ = R₃/Rₓ
where,
Rₓ = Unknown Resistance = ?
R₃ = 2500 Ω
R₂/R₁ = 0.625
R₁/R₂ = 1/0.625 = 1.6
Therefore,
1.6 = 2500 Ω/Rₓ
Rₓ = 2500 Ω/1.6
Rₓ = 1562.5 Ω