Lesson 3: Temperature and Heat Answers

A 440 kg roller coaster car is going 26 m/s when it reaches the lowest point on the track. If the car started from rest at the top of a hill, how much higher was that point on the track than the lowest point? (Use g = 9.80 m/s2, and ignore friction.)

What is the potential energy of a spring that is compressed 0.65 m by a 25 kg block if the spring constant is 95 N/m?

A box is released from rest and slides down a ramp in a closed system. Even though the box speeds up, its kinetic energy at the bottom of the ramp is less than the potential energy that it had at the top of the ramp.

Irving, a cat, has a favorite toy that is made up of a squeaky ball at the end of a string. The toy makes up a closed system. Irving’s owner dangles the toy so that the ball swings down and then swings back up again.

What does the law of conservation of energy state about energy in a closed system?

When an object is not in motion, it can still have a form of energy. What form of energy does an object have due to its distance from Earth?

A box is sliding along a frictionless surface and gets to a ramp. Disregarding friction, how fast should the box be going on the ground in order to slide up the ramp to a height of 2.5 meters, where it stops? (Use g = 9.8 m/s2.)

A 535 kg roller coaster car began at rest at the top of a 93.0 m hill. Now it is at the top of the first loop-de-loop.This roller coaster’s track is nearly frictionless, so resistance can be ignored. Using g = 9.8 m/s2, what best describes the roller coaster car when it is at the top of the loop-de-loop?

Disregarding air resistance, what is the speed of a ball dropped from 12 feet just before it hits the ground? (Use 1 ft = 0.30 m, and use g = 9.8 m/s2.)

A famous motorcycle company has just built its first electric model. Like all vehicles, the purpose of the motorcycle is to put out kinetic energy.

What best describes the energy in a closed system at the beginning of a day and the energy at the end of the same day? Check all that apply.Some energy can disappear after it has caused motion.Some energy can be changed from one form to another.Some energy can be lost to the environment around the system.The total initial energy will be equal to the total final energy.The total initial energy will be greater than the total final energy.Friction can cause energy to be destroyed during the day.Friction can cause the amount of thermal energy to increase.

For a group class project, students are building model roller coasters. Each roller coaster needs to begin at the top of the first hill, where a horizontal spring that is initially compressed 0.25 m will push a small car forward.Each group of students will choose a car and a spring to push the car and then build a track. The assignment is to make the car go 5.0 m/s when it reaches the bottom of the first hill. Four groups of students choose springs and build tracks as described in the table.Which group’s roller coaster will most likely make the car travel closest to 5.0 m/s when it is at the bottom of the first hill?

A 7.00 kg bowling ball is held 2.00 m above the ground. Using g = 9.80 m/s2, how much energy does the bowling ball have due to its position?