ELF Shape Lock

In which of the following situations would an object NOT experience an acceleration?

The object moves in a straight line at a high speed.

An object traveling at a slow speed and is speeding up.

An object traveling at a high speed but is slowing down.

The object travels as a projectile in a gravitational field with negligible air resistance.

The object moves along a circular path.

An object of mass m rests on a flat table. The earth pulls on this object with a force of magnitude mg. What is the reaction force to this pull?

The object pushing down on the table with force equal to the weight of the object (mg).

The table pulling upward on the Earth with force equal to weight of the object (mg)

The table pushing up on the object with force equal to the weight of the object (mg).

The object pulling upward on the Earth with force equal to the weight of the object (mg)

The table pushing down on the floor with force equal to weight of the object (mg).

A physics student sitting in the back of box truck notices that a tennis ball and string dangling from the compartment hangs at rest at 300 away from the vertical toward the back of the truck. Using this observation, the physics student can conclude that the truck is-

not accelerating because the string is at rest

accelerating backward

moving forward

moving backward

accelerating forward

Buddy pushes a snow blower mower across a horizontal patch of ground with a constant speed by applying a force P. The arrows in the diagram correctly indicate the directions but not necessarily the magnitudes of the various forces on the lawn mower. Which of the relations among the various force magnitudes, W, f, N, P is correct?

P > f and N < W

P = f and N > W

P < f and N = W

none of the above

P > f and N > W

A crate of toys (G) remains at rest on the sleigh as the sleigh is pulled up a hill with an increasing speed. The crate is not fastened down to the sleigh. What force is responsible for the crate's increase in speed up the hill?

15

25

the force of static friction of the sleigh on the crate

the contact force (normal force) of the sleigh on the crate

the gravitational force acting on the sleigh

no force is needed

the contact force (normal force) of the ground on the sleigh

G