Energy and Momentum Quiz Quizzes

Q. How much work is done by gravity when a 10 kg object falls for 5 s?

Q. In a rodeo, a cow herder must try to lasso a 1000 kg bull running at 6 m/s. If he wants to bring the cow to a stop in 2 m, what tension must the rope of his lasso be able to withstand?

Q. On larger scales—such as those larger than planet Earth—our formula for gravitational potential energy breaks down. We must replace it with a more general equation (this is completely analogous to the use of F = mg for weight on Earth, but for the gravitational attraction of celestial bodies).

Orbital potential energy for object 1 circling object 2 is given by , where G is the gravitational constant () and r is the distance between the objects. Given this information, what is the total mechanical energy of the earth as it revolves in a circle around the sun? The mass of Earth is approximately 6 × 10²⁴ kg, the mass of the sun is approximately 2 × 10³⁰ kg, and they are almost 150 million km apart.

Q. In reality, the distance between the earth and the sun varies, since the earth's orbit is elliptical. As the earth moves from point A to point B, which of the following quantities must decrease (or become more negative)?

Q. On long downhill stretches of major roads, there will often be runaway truck ramps—large uphill slopes designed to stop a truck if its brakes fail. Because of friction, these ramps can be a lot shorter than if they had to rely purely on conversion of kinetic energy to potential energy in order to stop a truck. If a 10,000 kg truck pulls onto a 30 m long runaway ramp with a 20º slope and a coefficient of friction of 0.8, what's the fastest the truck could be going and still be stopped safely?

Q. A 2013 Chevrolet Corvette Z1 weighs 1511 kg and can accelerate from 0 to 60 mph (26.8 m/s) in a mind-bogglingly fast 3.4 s. What's the average power used by its engine during that acceleration period?

Q. Often, roller coasters will use rubber wheels to slow a car down. If a roller coaster car goes down a 40 m drop and then hits a 8 m section of rubber brakes, what is the highest second hill it could make it over? Assume the track is frictionless except for the braking section, which has a coefficient of friction of 0.6.

Q. In a Newton's cradle, one ball is lifted up on a string and falls into a line of identical balls, transferring momentum through the line and into the last ball. Imagine a cradle with just two balls, of different masses. One weighing 20 g is lifted 5 cm up and released. How fast is the second ball, which weighs 40 g, traveling the instant after its hit by the first?

Q. Which of the following is NOT a type of potential energy?

Q. A Gauss rifle is a cool toy that uses magnets to accelerate a projectile via momentum transfer. In a typical rifle, there are several magnets lined up with two ball bearings stuck to the right side of each one. An extra ball bearing is released to the left of the first magnet, and in a split second the last ball bearing has shot out of the right end at high speed.

In a Gauss rifle with four stages, the distance between each magnet and ball bearing is 2 cm. The magnets can pull on the 1 g bearings with a force of 1 N, and the bearings collide with the magnets elastically. How fast does the final ball bearing leave the rifle?