Friction Quiz

Which vector diagram best represents a cart slowing down as it travels to the right on a horizontal surface?

• 1

• 2

• 3

• 4

A car’s performance is tested on various horizontal road surfaces. The brakes are applied, causing the rubber tires of the car to slide along the road without rolling. The tires encounter the greatest force of friction to stop the car on:

• dry concrete

• dry asphalt

• wet concrete

• wet asphalt

When a 12-newton horizontal force is applied to a box on a horizontal tabletop, the box remains at rest. The force of static friction acting on the box is:

• 1.0 N

• between 0 N and 12 N

• 12 N

• greater than 12 N

A box is pushed toward the right across a classroom floor. The force of friction on the box is directed to ward the:

• left

• right

• ceiling

A skier on waxed skis is pulled at constant speed across level snow by a horizontal force of 39 newtons. Calculate the normal force exerted on the skier.

• 981 N

• 39 N

• 279 N

• 780 N

What is the magnitude of the force needed to keep a 60-newton rubber block moving across level, dry as phalt in a straight line at a constant speed of 2 meters per second?

• 40 N

• 51 N

• 60 N

• 120 N

The force required to start an object sliding across a uniform horizontal surface is larger than the force required to keep the object sliding at a constant velocity. The magnitudes of the required forces are different in these situations because the force of kinetic friction:

• is greater than the force of static friction

• is less than the force of static friction

• increases as the speed of the object relative to the surface increases

• decreases as the speed of the object relative to the surface increases

A force of 10 newtons toward the right is exerted on a wooden crate initially moving to the right on a horizontal wooden floor. The crate weighs 25 newtons. Calculate the magnitude of the force of friction be tween the crate and the floor

• 7.5 N

• 10.5 N

• 3 N

• 2.5 N

On a flat level surface the Normal Force F_N is equal to the:

• Force of Friction

• Net Force

• Weight or F_g

• coefficient of friction

Surface area has:

• no effect on the coefficient of friction.

• very little effect on the coefficient of friction.

• some effect on the coefficient of friction.

• great effect on the coefficient of friction.