Physics Exam II ch 6 – Flashcards

Cassy can get more force on the bricks she breaks with a blow of her bare hand when _______. a. she does so with great determination b. she exerts follow through c. she toughens her hand beforehand d. her hand is made to bounce from the bricks

When a falling firecracker explodes, the momenta of its pieces _______. a. illustrate a case in which momentum is not conserved b. vectorally add to equal the initial momentum of the firecracker c. are conserved only if the fragments eject in one direction d. disintegrate

Which of the following has the largest momentum relative to the Earth's surface? a. a Mack truck parked in a parking lot b. a pickup truck speeding along a highway c. the Science building on campus d. a dog running down the street e. a tightrope walker crossing Niagara Falls

It is correct to say that impulse is equal to It is correct to say that impulse is equal to a. velocity multiplied by time. b. the force multiplied by the distance the force acts. c. momentum. d. the change in momentum it produces.

A car traveling along the highway needs a certain amount of force exerted on it to stop it in a certain distance. More stopping force is required when the car has a. more momentum. b. more mass. c. less stopping distance. d. all of these e. none of these

Padded dashboards in cars are safer in an accident than nonpadded ones because an occupant hitting the dash has a. increased time of impact. b. increased momentum. c. decreased impulse. d. decreased time of impact.

A 4 kg ball has a momentum of 12 kg m/s. What is the ball's speed? a. 48 m/s b. 4 m/s c. 12 m/s d. 3 m/s e. none of these

A ball is moving at 3 m/s and has a momentum of 48 kg m/s. What is the ball's mass? A ball is moving at 3 m/s and has a momentum of 48 kg m/s. What is the ball's mass? a. 4 kg b. 16 kg c. 144 kg d. 12 kg e. none of these

A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared to the force that stops the car, the force needed to stop the truck is a. greater. b. smaller. c. the same.

A karate expert executes a swift blow and breaks a cement block with her bare hand. The magnitude of the force experienced by her hand is a. zero. b. identical to the force applied to the block. c. less than the force applied to the cement block. d. more than the force applied to the block. e. impossible to predict without additional information.

A 1000-kg car moving at 10 m/s brakes to a stop in 5 s. The average braking force is a. 4000 N. b. 2000 N. c. 3000 N. d. 1000 N. e. 5000 N.

An astronaut , floating alone in outer space, throws a baseball. If the ball floats away at a speed of 20 meters per second, the astronaut will a. move in the opposite direction, but at a lower speed. b. move in the opposite direction but at a higher speed. c. move in the opposite direction at a speed of 20 m/s. d. not move as stated in any of the above choices.

A 5000-kg freight car moving at 2 m/s runs into a 10,000-kg freight car at rest. They couple upon collision and move away as one body at a. 1/3 m/s. b. 1 m/s. c. 2 m/s. d. 2/3 m/s.

What is the magnitude of the impulse on an 8.8-kg ball rolling at 2.4 m/s when it bumps into a pillow and stops?

A 2.00-kg blob of putty moving at 2.00 m/s slams into a 5.00-g blob of putty at rest. Calculate the speed of the two stuck-together blobs of putty immediately after colliding

Joanne drives her car with a mass of 1000 kg at a speed of 19 m/s .Find a road friction force that is need to bring her car to a halt in 8.0 s .

Two vehicles with equal magnitudes of momentum traveling at right angles to each other undergo an inelastic collision. The combined wreck moves in a direction a. at 45 degrees to the direction of either car before collision. b. at some angle other than 45 degrees. c. parallel to either of the cars before collision.

Two 5000-kg rail cars roll without friction (one at 1 m/s, the other at 2 m/s) toward each other on a level track. They collide, couple, and roll together with a combined momentum of a. 5000 kg m/s. b. zero. c. 15,000 kg m/s. d. 10,000 kg m/s.