Exam 3 Flashcards
When a car is weighed, it is driven slowly on a horizontal floor over a scale that records a reading as the front wheels go over the scale, and then records a second reading as the rear wheels go over the scale. The weight of the car is equal to …
the sum of the two weights
A 75-kg lighting fixture is hung from wires of identical size and shape (aluminum, brass, or copper). The values of Young’s modulus for these metals are 0.70 × 10^11 Pa (aluminum), 0.91 × 10^11 (brass), and 1.1 × 10^11 (copper). Which wire would stretch the least distance?
copper
Two wires are made out of the same metal, but one wire is twice as long as the other wire. Which wire will have the greatest elastic modulus?
it will be the same for both wires
A rubber ball and a lump of clay have equal masses. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The clay sticks to the wall. Which one of these objects experiences the greater momentum change?
the ball
A tiger is running in a straight line. If we double both the mass and speed of the tiger, the magnitude of its momentum will increase by what factor?
4
You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You have two choices about what to do with the ball: either catch the ball or deflect it back toward your friend with the same speed as it was initially thrown. Which choice should you make in order to maximize your speed on the skateboard?
deflect the ball back
A 5-kg ball collides inelastically head-on with a 10-kg ball, which is initially stationary. Which of the following statements is true?
The magnitude of the change of velocity the 5-kg ball experiences is greater than that of the 10-kg ball.
The magnitude of the change of the momentum of the 5-kg ball is equal to the magnitude of the change of momentum of the 10-kg ball.
A merry-go-round spins freely when Diego moves quickly to the center along a radius of the merry-go-round. As he does this, it is true to say that …
the moment of inertia of the system decreases and the angular speed increases
Person X pushes twice as hard against a stationary brick wall as Person Y. What statement is correct?
both do zero work
You are your friend, who weighs the same as you, want to go to the top of the Eiffel Tower. Your friend takes the elevator straight up. You decide to walk up the spiral stairway, taking longer to do so. Compare the gravitational potential energy of you and your friend, after you both reach the top.
Both of you have the same amount of gravitational potential energy at the top.
When you drop a pebble from height H, it reaches the ground with speed V if there is no air resistance. From what height should you drop it so it will reach the ground with twice the speed?
4H
Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. If there is no air resistance, when they hit the ground …
the heavier one will have twice the kinetic energy of the lighter one
A lightweight object and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill with no air resistance. Which object rises to a greater height?
They both slide to exactly the same height.
Joe and Bill throw identical balls vertically upward. Joe throws his ball with an initial speed twice as high as Bill. If there is no air resistance, the maximum height of Joe’s ball will be …
four times that of Bill’s ball
If the units of your answer are kg ∙ m2/s3, which of the following types of quantities could your answer be?
power (W)
