BMST Newton's Laws of Motion 5

Question 1

A person stands on a scale in an elevator accelerating upward. The scale reading will be:

Accepted Answer

Greater than their actual weight

Answer

Upward acceleration requires a net upward force, so the normal force (scale reading) exceeds actual weight.

Question 2

What is the net force on an object moving at constant velocity?

Accepted Answer

Zero

Answer

Constant velocity means zero acceleration; by Newton's Second Law, net force = ma = m(0) = 0.

Question 3

Two forces act on a box: 15 N to the right and 5 N to the left. If the box has a mass of 2 kg, what is its acceleration?

Accepted Answer

10 m/s² to the right

Answer

Net force = 15 − 5 = 10 N right; a = F/m = 10/2 = 5 m/s²... wait: a = 10 N / 2 kg = 5 m/s² to the right.

Question 4

Which of Newton's laws is sometimes called the 'law of inertia'?

Accepted Answer

Newton's First Law

Answer

Newton's First Law describes inertia — objects maintain their state of rest or uniform motion unless acted on by a net force.

Question 5

A bullet fired from a rifle causes the rifle to recoil backward. Which law explains this?

Accepted Answer

Newton's Third Law

Answer

The rifle exerts force on the bullet forward; the bullet exerts an equal and opposite force on the rifle backward (Third Law).

BMST - Basic Math and Science Test Practice Test