Physics Exam 3 Conceptual Questions
A stock person at the local grocery store has a job consisting of the following five segments: (1) picking up boxes of tomatoes from the stockroom floor (2) accelerating to a comfortable speed (3) carrying the boxes to the tomato display at constant speed (4) decelerating to a stop (5) lowering the boxes slowly to the floor. During which of the five segments of the job does the stock person do positive work on the boxes?
(1) and (2)
https://session.masteringphysics.com/problemAsset/1384312/3/knight_Figure_11_26.jpg How much work is done by the environment in the process shown in the figure?
-1.00J
The left end of a spring is attached to a wall. When Bob pulls on the right end with a 200 N force, he stretches the spring by 32 cm . The same spring is then used for a tug-of-war between Bob and Carlos. Each pulls on his end of the spring with a 200 N force. -How far does the spring stretch?
32 cm
Two balls of clay of known masses hang from the ceiling on massless strings of equal length. They barely touch when both hang at rest. One ball is pulled back until its string is at 45 ∘ , then released. It swings down, collides with the second ball, and they stick together. To determine the angle to which the balls swing on the opposite side, would you invoke: conservation of momentum, conservation of mechanical energy, both, either but not both, or these principles alone are not sufficient to find the angle?
Both
A 4.0-kg object is moving with speed 2.0 m/s. A 1.0-kg object is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?
Both objects travel the same distance.
Two ice skaters, Paula and Ricardo, push off from each other. Ricardo weighs more than Paula. -Which skater, if either, has the greater momentum after the push-off?
Both skaters have momentums of equal magnitude.
Rank in order, from most to least, the elastic potential energy (Us)a to (Us)d stored in the springs of the figure(Figure 1) . https://session.masteringphysics.com/problemAsset/1385659/4/10.Q11.jpg
Elastic potential energy most to least: d>c>a=b
https://session.masteringphysics.com/problemAsset/1384312/3/knight_Figure_11_26.jpg Is energy transferred from the environment to the system or from the system to the environment?
Energy is transferred from the system to the environment.
Two men, Joel and Jerry, push against a wall. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do.
Neither of them does any work.
If the force on a particle at some point in space is zero, must its potential energy also be zero at that point?
No
If the potential energy of a particle at some point in space is zero, must the force on it also be zero at that point?
No
Two ice skaters, Paula and Ricardo, push off from each other. Ricardo weighs more than Paula. -Which skater, if either, has the greater speed after the push-off?
Paula has the greater speed.
A block of mass m slides down a frictionless track, then around the inside of a circular loop-the-loop of radius R. From what minimum height h must the block start to make it around the loop without falling off? Give your answer as a multiple of R.
h/R = 2.50
A baseball is thrown vertically upward and feels no air resistance. As it is rising
its momentum is not conserved, but its mechanical energy is conserved.
On a smooth horizontal floor, an object slides into a spring which is attached to another mass that is initially stationary. When the spring is most compressed, both objects are moving at the same speed. Ignoring friction, what is conserved during this interaction
momentum and mechanical energy
The three balls in the figure(Figure 1) which have equal masses, are fired with equal speeds from the same height above the ground https://session.masteringphysics.com/problemAsset/1383347/3/10.Q7.jpg
their speeds as they hit the ground will all be the same.
A process occurs in which a system's potential energy increases while the environment does work on the system.
there is not enought information
The three balls in the figure(Figure 1) which have equal masses, are fired with equal speeds at the angles shown https://session.masteringphysics.com/problemAsset/1383348/3/10.Q8.jpg
they will all reach the horizontal line with the same speed
A mother has four times the mass of her young son. Both are running with the same kinetic energy. What is the ratio vs/vm other of their speeds?
vs/vm = 2.0
Jacques and George meet in the middle of a lake while paddling in their canoes. They come to a complete stop and talk for a while. When they are ready to leave, Jacques pushes George's canoe with a force F⃗ to separate the two canoes. What is correct to say about the final momentum and kinetic energy of the system(consisting of the two canoes and the men in them) if we can neglect any resistance due to the water?
The final momentum is zero but the final kinetic energy is positive.
If a force always acts perpendicular to an object's direction of motion, that force cannot change the object's kinetic energy.
True
A roller-coaster car rolls down a frictionless track, reaching speed v0 at the bottom. If you want the car to go twice as fast at the bottom, by what factor must you increase the height of the track?
You must increase the track height by a factor of 4
You drop a ball from a high balcony and it falls freely. Does the ball's kinetic energy increase by equal amounts in equal time intervals, or by equal amounts in equal distances
by equal amounts in equal distances
