WTMA Force, Motion, and Friction 4

Question 1

A heavy crate and a light box are pushed with the same force on the same surface. Which accelerates faster?

Accepted Answer

The light box

Answer

From Newton's second law (a = F/m), a smaller mass produces greater acceleration when the same force is applied.

Question 2

Oil is applied to a machine's moving parts. What effect does this have on friction?

Accepted Answer

It reduces friction by creating a lubricating film

Answer

Lubrication separates surfaces with a thin oil film, greatly reducing the coefficient of friction between moving parts.

Question 3

A car goes around a curved road at high speed. What force keeps it on the curved path?

Accepted Answer

Friction between tires and road

Answer

Friction between the tires and the road provides the centripetal force needed to keep the car moving in a curved path.

Question 4

Which change would NOT reduce the friction between two sliding surfaces?

Accepted Answer

Increasing the contact surface area

Answer

For most surfaces, friction force is independent of contact area — only the normal force and coefficient of friction matter.

Question 5

A train traveling at constant speed on level track has its engines providing 50,000 N of force. What is the total friction/resistance force?

Accepted Answer

50,000 N

Answer

At constant velocity, net force is zero, so resistance forces exactly equal the engine's driving force of 50,000 N.

WTMA - Wiesen Test of Mechanical Aptitude Practice Test