Answer: option b.
Explanation:
The kinetic energy of a spring with constant K is calculated as:
kinetic energy = (k/2)*x^2
Where x^2 is the displacement of the spring with respect to it's rest position.
This can be written as a function like:
x = A*cos(2*pi*f*t)
where:
A is the amplitude (the maximum distance that the spring can move in each direction)
f is the frequency (and 2*pi*f is the angular frequency)
and t is the variable, it represents the time.
Replacing this in the kinetic energy equation, we get:
kinetic energy = (k/2)*(A*cos(2*pi*f*t))^2
This is the same as the option b: b. 1/2kA^2cos^2(2πft)
Then the corrrect option is b.
Answer:
A. the tendency of moving objects to stay in motion
Explanation:
just did it on ap3x
Answer:
Explanation:
Let the mass of bullet is m, initial velocity of bullet is vi and c be the specific heat of the bullet.
Kinetic energy, K = 1/2 mvi^2
According to the question, 50% of the kinetic energy is equal to the heat energy absorbed by the bullet.
50% of K = mass of bullet x specific heat x rise in temperature
1/4 mvi^2 = m x c x ΔT
The complete question is;
James Joule (after whom the unit of energy is named) claimed that the water at the bottom of Niagara Falls should be warmer than the water at the top, 51 m above the bottom. He reasoned that the falling water would transform its gravitational potential energy at the top into thermal energy at the bottom, where turbulence brings the water almost to a halt. If this transformation is the only process occurring, how much warmer will the water at the bottom be?
Answer:
Water becomes warmer by a temperature of ΔT = 0.119 K
Explanation:
If we assume that gravitational kinetic energy will be converyrf into thermal enrgy, we will have;
Q = U
So, m•c_w•ΔT = mgh
Where;
c_w is specific heat capacity of water with a value of 4184 J/Kg.K
ΔT is change in temperature indicating how warmer the water will be. Thus making ΔT the subject, we have;
ΔT = gh/c_w
So, ΔT = 9.8 x 51/4184 = 0.119 K