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Example Questions
Example Question #31 : Gravitational Potential Energy
The train car on the rollercoaster above has a mass of , and the potential energy at the top of the first hill is .
What is the height of the hill?
Potential energy is equal to the mass of an object multiplied by gravity multiplied by the height at which the object rests. This is demonstrated by the following equation:
In this problem, you are given the mass and potential energy of the object. Gravity is a constant, therefore there is a single variable left to solve for and this is the height at which the object rests. By plugging in the given values the height is found to be:
Example Question #31 : Gravitational Potential Energy
A specialized hot air balloon is high. Determine the initial velocity needed for a supply package to be launched straight up to reach the balloon. Ignore air resistance.
None of these
The package will need to at least gain in height, thus it will need to gain
gravitational potential energy
When it is launched, it will have a kinetic energy equal to
Since energy is conserved:
Solving for
Example Question #31 : Gravitational Potential Energy
A ball with a mass of is released from a ramp with a height of and the ball starts to roll downward. What is the velocity of the ball at the bottom of the ramp? (Assume no friction or air resistance).
All of the potential energy that the ball has at the top of the ramp is converted into kinetic energy. Knowing this, we can determine the velocity when the ball is moving at the bottom of the ramp by assuming all the potential energy is converted into kinetic energy.
Example Question #31 : Gravitational Potential Energy
A jet is flying at , above the ocean. A bowling ball is dropped from the jet. At what velocity does the ball strike the water? Air resistance may be ignored.
None of these
The ball will gain velocity in the vertical direction due to gravity.
The ball will also have velocity due to it's initial horizontal velocity
using
Combining equations and plugging in values:
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