A rock thrown with a horizontal velocity of 20m/s from a cliff that is 125m above level ground. If air resistance is negligible,
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Answer:
Em₀ = U = m g h , Em_{f} = K = ½ m v²
Explanation:
When a car is on a ramp it has a certain amount of mechanical energy. At the highest point of the ramp the mechanical energy is fully potential given by
Em₀ = U = m g h
As part of this energy descends down the ramp, part of this energy is transformed into kinetic energy and has one part of each, even though the sum remains the initial energy
Em = K + U = ½ m v² + mg y
y <h
when it reaches the bottom of the ramp it has no height therefore there is no potential energy, all of it has been transformed into kinetic energy
Em_{f} = K = ½ m v²
This energy transformation is in the case that the friction force is zero.
If there is a friction force, it performs work against the low car, it is reflected in an increase in the internal energy (temperature) of the car. In this case the energy in the lower part is less than the initial one by a factor
= - fr L
therefore the numeraire values of the velocity are lower, due to the energy lost by friction.
Answer:
Explanation:
Acceleration can be found by dividing the change in velocity by the time.
where Vf is the final velocity, Vi is the initial velocity, and t is the time.
Since the car came to a complete stop, it's final velocity was 0 meters per second.
The initial velocity was 22 meters per second.
The time was 2.0 seconds.
Substitute the values into the formula.
Subtract in the numerator first.
- 0 m/s- 22 m/s = -22 m/s
Divide.
The acceleration of the car was -11 meters per square second. The negative acceleration indicates slowing down/stopping.