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Ballistics experts are testing projectiles. Projectile A has mass m and is fired with a velocity 2v. Projectile B has mass 2m and is fired with velocity v. Projectile C has mass m and is fired at a speed v. Which projectile has the greatest kinetic energy?
(A) Projectile A
(B) Projectile B
(C) Projectile C
(D) Both A and B have equal kinetic energy
A block is on a ramp, with no objects touching it other than the ramp. The block slides down the ramp at a constant velocity. This means that...
(A) The ramp is frictionless
(B) The magnitude of the force of friction is equal to the magnitude of the component of the weight acting parallel to the surface of the ramp
(C) The magnitude of the force of friction is equal to the weight of the block
(D) The magnitude of the force of friction is equal to the magnitude of the normal force between the block and the ramp.
A block with an unknown mass is being pushed on by a force equal to F = 260 N, applied to the box at an angle 20 degrees from horizontal. There is significant friction between the block and the surface, which prevents the box from sliding.
The coefficient of static friction between the box and the surface is most nearly…
(A) 0.34
(B) 0.55
(C) 0.94
(D) It cannot be determined
A block with an unknown mass is being pushed on by a force equal to F = 260 N, applied to the box at an angle 20 degrees from horizontal. There is significant friction between the block and the surface, which prevents the box from sliding.
The magnitude of the force of static friction acting on the block is most nearly…
(A) 89 N
(B) 244 N
(C) 260 N
(D) It cannot be determined
Two boxes, mass M and 3M are stacked on top of each other. The stack of boxes is placed inside an elevator which is accelerating upwards.
When the elevator accelerates upward with an acceleration equal to a, which of the following will correctly give the magnitude of the force which the bottom box applies to the top box?
(A) 3Mg
(B) 3Ma
(C) 3M(a-g)
(D) 3M(a+g)
Two boxes, mass M and 3M are stacked on top of each other. The stack of boxes is placed inside an elevator which is accelerating upwards
Which box has a larger upward force (normal force) acting on it?
(A) The box of mass 3M
(B) The box of mass M
(C) The two boxes experience equal sized upward normal forces
(D) It cannot be determined
Two boxes, mass M and 3M are stacked on top of each other. The stack of boxes is placed inside an elevator which is accelerating upwards.
How does the magnitude of the force exerted by the top box on the bottom box compare to the magnitude of the force exerted by the bottom box on the top box?
(A) The top box exerts a force which is 3 times larger
(B) The bottom box exerts a force which is 3 times larger
(C) The two forces are equal
(D) The top box exerts a larger force, but it is not necessarily 3 times larger
Two objects, 1 and 2, are moving along a flat, horizontal track. Object 1 covers a distance 8d in a time of 2t seconds. Object 2 travels a distance of d in a time of t seconds. How does the speed of object 1 (v1) compare to the speed of object 2 (v2)?
(A) 4v1 = v2
(B) v1 = 4v2
(C) v1 = 8v2
(D) v1 = -v2
Two objects, X and Y, accelerate from rest with the same constant acceleration. Object X accelerates for three times the amount of time as object Y. Which of the following is true of these objects at the end of their respective periods of acceleration?
(A) The final speed of object X is the same as object Y.
(B) The final speed of object X is three times faster than object Y.
(C) Object X has traveled twice as far as object Y.
(D) Object X has traveled four times as far as object Y.
You have two small metal balls. You drop the first ball and throw the other one in the downward direction. The two balls are released at the same time, from the same height. Choose the statement which is not correct.
(A) The second ball will spend less time in flight.
(B) The first ball will have a slower final speed when it reaches the ground.
(C) The second ball will have a larger acceleration while falling.
(D) Both balls will have the same acceleration while falling.
