Energy - Concepts
When a rock is dropped from a height of 3 meters, the gravitational potential energy of the rock is converted to kinetic energy. When the rock hits the floor and does not bounce, what happens to the kinetic energy of the rock?
A) The energy is destroyed and cannot change form.
B) The energy is converted to heat and sound.
C) The energy is converted to chemical energy.
D) The energy is returned to gravitational energy.
B) The energy is converted to heat and sound.
What type of collision occurs when both momentum and energy are conserved?
Elastic Collision
State the equation to calculate the work done when given a force and displacement.
W=F*d
An object with a height of 50 meters has 100 joules of potential energy. What is the kinetic energy of the object when it has fallen 25 meters?
50 Joules
Calculate the kinetic energy of a 8 kg ball dropped from a height of 12 m just before it hits the ground.
960 J
A skier begins at the top of a slope with 50 J of potential energy. As the skier descends and reaches the bottom, the total mechanical energy of the system at the bottom will be equal to 50 J, greater than 50 J, or less than 50 J.
equal to 50 J
A 15000 kg railroad car travels on a horizontal track with a constant speed of 12 m/s. A 6000 kg load is dropped onto the car. What will be the car’s speed?
8.57 m/s
A horse pulls a carriage by applying 89,000 J of work over 33 m. Find the force the horse pulled with.
2629.97 N
An object with a height of 50 meters has 100 joules of potential energy. What is the total energy of the system when it has fallen 25 meters?
100 Joules
A 1200 kg elevator gains 600,000 J of gravitational potential energy as it moves from the ground floor to the top of a building. Compute the height of the building.
50 m
When a spring-loaded toy car is released from a compressed position, what form of energy is primarily converted into kinetic energy as the car moves forward?
A) Gravitational potential energy
B) Elastic potential energy
C) Chemical potential energy
D) Thermal energy
B) Elastic Potential Energy
A 2 kg marble moving to the right at 0.10 m/s makes an elastic head on collision with a 4 kg shooter marble moving to the left at 0.50 m/s. After the collision, the smaller marbles moves to the left at 0.25 m/s. What is the velocity of the 4 kg marble after the collision?
-.33 m/s
A light plane travels a distance of 150 m along a runway before takeoff. Find the work done by the plane engine if it is applying a force of 13500 N.
2025000 J
A spring with spring constant 270 N/m has 5 J of energy stored in it. How much is it compressed?
0.19 m
A 3.0-kg block of ice held against a spring with a force constant of 125 N/m. The spring is compressed by .12 m. Calculate the speed of the ice just as it leaves the spring.
0.77 m/s
When a person jumps off a diving board, what form of energy is initially converted into gravitational potential energy as they ascend?
A) Elastic potential energy
B) Thermal Energy
C) Kinetic Energy
D) Nuclear potential energy
C) Kinetic Energy
A 480 N surfer runs west with a velocity of 5.0 m/s towards a 12 kg skateboard moving east with a velocity of 3.0 m/s, and jumps on. Determine the combined speed and direction of the surfer and skateboard.
3.4 m/s west
Someone picks up a 2 kg box off of the ground, 1 meter high. How much work did the person do?
20 J
A simple pendulum consists of a bob of mass 0.085 kg attached to a string of length 1.5 m. The pendulum is raised to its highest point and released so that it oscillates with a period of 1.2 seconds. What is the surface gravity where the pendulum is oscillating?
41.60 m/s^2
A small truck is equipped with a rear bumper that has a spring constant of 5x10^7 N/m. The bumper can be compressed up to 15 cm without causing damage to the truck. What is the maximum velocity with which a solid 1000-kg car can collide with the bumper without causing damage to the truck?
33.54 m/s
What happens to the total mechanical energy of a mass-spring system as it undergoes damped oscillations due to friction?
A) It increases over time
B) It decreases over time.
C) It remains constant.
D) It oscillates between potential and kinetic energy without change.
B) Decreases
To investigate momentum, one physics student rolls a 0.05 kg tennis ball to the right at 14 m/s towards a ping pong ball that another physics student rolls 8 m/s to the left. After the collision, the tennis ball moves right with a velocity of 9 m/s, and the ping pong rolls right at 17 m/s. Find the mass of the ping pong ball.
0.01 kg
Someone walks 500 meters carrying a 2 kg box. How much work did the person do?
No work was done.
A spring with a spring constant of 350 N/m is used in a physics experiment. If the spring oscillates with a period of 1.5 seconds when a mass is attached to it, what is the mass of the object at the end of the spring?
20.16 kg
A lava bomb is observed being launched straight up from a volcano on another planet. The lava bomb reaches a height of 1600 m above the volcano after leaving with an initial velocity of 40 m/s. What is the surface gravity on this planet?
0.5 m/s^2