Practice Newton's Second Law in Physics

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

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Quick Recap

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass, with the acceleration pointing in the same direction as the net force.

Push harder and you get faster acceleration; heavier object means slower acceleration for the same push.

Showing a random 20 of 50 problems.

Example 1

medium
A 0.2 kg0.2\text{ kg} ball is struck and reaches 30 m/s30\text{ m/s} from rest in 0.01 s0.01\text{ s}. Find the average force.

Example 2

hard
A 1000 kg1000 \text{ kg} car experiences a net forward force whose magnitude grows linearly from 00 at t=0t=0 to 2000 N2000 \text{ N} at t=4 st=4 \text{ s}. What is the car's acceleration at t=2 st = 2 \text{ s}?

Example 3

easy
Is F=maF = ma a vector equation or a scalar equation?

Example 4

hard
A 70 kg70 \text{ kg} person stands in an elevator that accelerates downward at 2 m/s22 \text{ m/s}^2. What is the apparent weight (normal force) on the person? Use g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Example 5

medium
A 0.5 kg0.5 \text{ kg} ball is dropped from rest and falls freely ignoring air resistance (g=9.8 m/s2g = 9.8 \text{ m/s}^2). What is the net force on the ball as it falls?

Example 6

medium
An elevator of mass 800 kg800 \text{ kg} accelerates upward at 1.5 m/s21.5 \text{ m/s}^2. Find the tension in the supporting cable. Use g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Example 7

medium
A 1500 kg1500 \text{ kg} rocket experiences 25,000 N25{,}000 \text{ N} thrust upward and weighs 14,700 N14{,}700 \text{ N}. Find its upward acceleration. Use g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Example 8

easy
Write the SI unit of force in base units.

Example 9

medium
If both mass and net force double, the acceleration is multiplied by ____.

Example 10

hard
A 2 kg2 \text{ kg} object's velocity changes from v⃗i=(3,0) m/s\vec{v}_i = (3, 0) \text{ m/s} to v⃗f=(3,4) m/s\vec{v}_f = (3, 4) \text{ m/s} over 2 s2 \text{ s}. Find the magnitude of the average net force.

Example 11

easy
If net force doubles and mass stays the same, what happens to acceleration?

Example 12

easy
What is the acceleration of a 6 kg6\text{ kg} object with a 0 N0\text{ N} net force?

Example 13

medium
A 3 kg3 \text{ kg} block on a frictionless table is pulled by T=12 NT = 12 \text{ N} horizontally while a 6 N6 \text{ N} horizontal drag opposes the motion. Find the acceleration.

Example 14

easy
An object of mass 0.5 kg0.5 \text{ kg} experiences a net force of 4 N4 \text{ N}. Find its acceleration.

Example 15

hard
Two blocks (m1=3 kgm_1 = 3 \text{ kg} on top of m2=5 kgm_2 = 5 \text{ kg}) sit on a frictionless floor. A horizontal 32 N32 \text{ N} force pushes m2m_2. Friction between the blocks is enough to keep m1m_1 from sliding. Find the system acceleration and the friction on m1m_1.

Example 16

medium
A 5 kg5\text{ kg} object on a flat floor (g=10g=10, μ=0.2\mu=0.2) is pushed with 30 N30\text{ N}. Find its acceleration.

Example 17

medium
A 1200 kg1200 \text{ kg} car accelerates from rest to 20 m/s20 \text{ m/s} in 8 seconds8 \text{ seconds}. What net force is required?

Example 18

challenge
A 1200 kg1200 \text{ kg} car on level ground experiences a drag force Fd=bvF_d = bv with b=60 N⋅s/mb = 60 \text{ N}\cdot\text{s/m} and a constant engine force of 3000 N3000 \text{ N}. What is the car's terminal (top) speed?

Example 19

challenge
A 5 kg5 \text{ kg} block on a frictionless 30°30° incline is connected over a pulley to a hanging 3 kg3 \text{ kg} block. Find the system acceleration. Use g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Example 20

medium
A constant 6 N6\text{ N} net force acts on a 3 kg3\text{ kg} cart for 4 s4\text{ s} from rest. Find its final speed.
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