Newton's First Law Physics Example 1

Follow the full solution, then compare it with the other examples linked below.

Example 1

easy
A book rests on a table. The weight of the book is 15 N15 \text{ N} downward. What is the normal force exerted by the table, and what is the net force on the book?

Solution

  1. 1
    The book is at rest, so by Newton's first law, the net force must be zero.
  2. 2
    The normal force must balance the weight: N=W=15 N upwardN = W = 15 \text{ N upward}
  3. 3
    Net force: Fnet=N−W=15−15=0 NF_{\text{net}} = N - W = 15 - 15 = 0 \text{ N}

Answer

N=15 N upward,Fnet=0 NN = 15 \text{ N upward}, \quad F_{\text{net}} = 0 \text{ N}
Newton's first law states that an object at rest stays at rest unless acted on by a net external force. A book on a table is in equilibrium because the normal force balances gravity.

About Newton's First Law

An object at rest stays at rest, and an object in motion continues moving at constant velocity in a straight line, unless acted upon by.

Learn more about Newton's First Law →

More Newton's First Law Examples

Example 2 medium

A hockey puck slides across a frictionless ice surface at [formula]. What is the puck's velocity aft

Example 3 easy

A car travels at a constant velocity of [formula] on a straight road. What is the net force acting o

Example 4 medium

A bus travels at [formula] and brakes suddenly. A backpack on the floor slides forward. According to

← All Newton's First Law Examples Newton's First Law Concept