Practice Force in Physics

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

A push or pull interaction between two objects that can cause a change in an object's velocity (speed or direction), described as a vector quantity.

Anything that makes something move, stop, speed up, slow down, or change direction.

Showing a random 20 of 50 problems.

Example 1

easy

A net force of

18 \text{ N}

acts on a

6 \text{ kg}

object. What is its acceleration?

Example 2

medium

5\text{ kg}

box has a

30\text{ N}

push forward and

10\text{ N}

friction back. Find the acceleration.

Net force = 30 − 10 = 20 N → a = 20/5 = 4 m/s².

Example 3

medium

1500 \text{ kg}

car accelerates from rest to

20 \text{ m/s}

8 \text{ s}

. What average net force acted on it?

Example 4

easy

A book rests on a table at constant rest. What is the net force on it?

Equal and opposite forces → F_net = 0 N.

Example 5

hard

5 \text{ kg}

block accelerates from

2 \text{ m/s}

8 \text{ m/s}

over a distance of

15 \text{ m}

. Find the net force on it.

Example 6

easy

A force of

12 \text{ N}

acts on a

3 \text{ kg}

object. What acceleration does the object experience?

Example 7

hard

Two ropes pull a

5 \text{ kg}

ring:

30 \text{ N}

0^\circ

(east) and

40 \text{ N}

90^\circ

(north). Find the magnitude of the ring's acceleration.

Example 8

hard

Two blocks of masses

3 \text{ kg}

and

5 \text{ kg}

are in contact on a frictionless surface. A horizontal force of

16 \text{ N}

pushes the

3 \text{ kg}

block. Find the contact force between the blocks.

Example 9

easy

Does a force always cause motion to start?

Example 10

hard

2 \text{ kg}

block on a frictionless incline of

30^\circ

is held in place by a rope parallel to the slope. Find the tension in the rope. Use

g = 10 \text{ m/s}^2

T = mg sin 30° = 2 × 10 × 0.5 = 10 N.

Example 11

hard

0.4 \text{ kg}

ball is whirled in a horizontal circle of radius

0.5 \text{ m}

5 \text{ m/s}

. Find the centripetal force.

Example 12

medium

If the net force on an object is doubled while its mass stays the same, how does the acceleration change?

Example 13

medium

2\text{ kg}

object goes from

0

6\text{ m/s}

3\text{ s}

. Find the net force.

Example 14

easy

Name the SI unit of force.

Example 15

easy

5 \text{ kg}

box is pushed across a floor with a force of

20 \text{ N}

. If there is no friction, what is the acceleration of the box?

No friction — the 20 N push is the only horizontal force, so a = F/m = 20/5 = 4 m/s².

Example 16

medium

A horizontal force of

50 \text{ N}

accelerates a

10 \text{ kg}

box at

3 \text{ m/s}^2

on a rough floor. Find the friction force.

F_net = ma = 30 N; friction f = 50 − 30 = 20 N.

Example 17

medium

An object of unknown mass accelerates at

2 \text{ m/s}^2

under a

14 \text{ N}

net force. Find its mass.

Example 18

challenge

3\text{ kg}

block on a frictionless ramp has a gravity component of

15\text{ N}

along the slope. Find its acceleration along the ramp.

The 15 N slope component is the net force → a = 15/3 = 5 m/s² down the slope.

Example 19

medium

0.2 \text{ kg}

apple sits in your hand at rest. What is the net force on the apple, and what upward force does your hand provide? Use

g = 9.8 \text{ m/s}^2

At rest: F_hand = W = mg = 0.2 × 9.8 = 1.96 N upward.

Example 20

medium

2.5 \text{ kg}

drone speeds up from

4 \text{ m/s}

10 \text{ m/s}

3 \text{ s}

while flying straight. What net force acts on the drone?

Drone accelerates at 2 m/s², so F_net = ma = 2.5 × 2 = 5 N.

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Related Concepts

Acceleration Mass Newton's First Law Newton's Second Law Newton's Third Law