Practice Weight 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 gravitational force acting on an object due to its mass, directed toward the center of a massive body.

How hard gravity pulls you toward the ground — it changes on different planets.

Showing a random 20 of 50 problems.

Example 1

easy
A textbook weighs 14.7 N14.7 \text{ N} on Earth. What is its mass? Use g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Example 2

medium
What is the weight of 1 kg1 \text{ kg} on Earth, in newtons, to two decimal places? Use g=9.81 m/s2g = 9.81 \text{ m/s}^2.

Example 3

medium
A scale reads WW for a stationary 40 kg40 \text{ kg} box. The same box, placed in an elevator accelerating upward at 2 m/s22 \text{ m/s}^2, reads W′W'. Compute both. Use g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Example 4

easy
What is the SI unit of weight?

Example 5

medium
A 70 kg70 \text{ kg} astronaut stands on a planet where her weight reads 560 N560 \text{ N}. What is the gravitational acceleration on that planet?

Example 6

easy
A 10 kg10\text{ kg} object is on the Moon, g=1.6 m/s2g=1.6\text{ m/s}^2. Find its weight.

Example 7

easy
An object's weight is 60 N60\text{ N} on Earth (g=10 m/s2g=10\text{ m/s}^2). Find its mass.

Example 8

easy
What is the weight of a 12 kg12 \text{ kg} object on Earth? Use g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Example 9

easy
A scale at the equator reads slightly less than a scale at the North Pole for the same mass. Why?

Example 10

challenge
A 50 kg50\text{ kg} person rides an elevator accelerating downward at 2 m/s22\text{ m/s}^2 (g=9.8g=9.8). Find their apparent weight.

Example 11

hard
Using Newton's law of universal gravitation, find the weight of a 1.0 kg1.0 \text{ kg} mass at Earth's surface. Earth mass M=5.97×1024 kgM = 5.97 \times 10^{24} \text{ kg}, radius R=6.37×106 mR = 6.37 \times 10^6 \text{ m}, G=6.67×10−11 N\cdotpm2/kg2G = 6.67 \times 10^{-11} \text{ N·m}^2/\text{kg}^2.

Example 12

medium
An object's mass is 8 kg8 \text{ kg}. On a planet where g=12 m/s2g = 12 \text{ m/s}^2, what is its weight?

Example 13

challenge
A 70 kg70\text{ kg} astronaut stands on a scale in a spacecraft accelerating upward at 4 m/s24\text{ m/s}^2 far from gravity (g≈0g\approx 0). What does the scale read?

Example 14

hard
A box of mass 20 kg20 \text{ kg} is being lifted by a rope at constant velocity. What is the tension in the rope? Use g=9.8 m/s2g = 9.8 \text{ m/s}^2.

Example 15

medium
A bag of sugar reads 4.9 N4.9 \text{ N} on an Earth scale (g=9.8 m/s2g = 9.8 \text{ m/s}^2). How many grams of sugar is that?

Example 16

easy
True or false: A 10 kg10 \text{ kg} rock on Mars has the same mass as on Earth.

Example 17

easy
An apple has mass 0.2 kg0.2 \text{ kg}. What is its weight on Earth (g=9.8 m/s2g = 9.8 \text{ m/s}^2)?

Example 18

challenge
An object weighs 100 N100\text{ N} at Earth's surface. At a height where gg is one-quarter as strong, find its weight.

Example 19

medium
A 2 kg2\text{ kg} object hangs from two cases: at rest, then accelerating up at g=9.8g=9.8 unchanged. What is its weight either way?

Example 20

hard
A person weighs 686 N686 \text{ N} on Earth (g=9.8 m/s2g = 9.8 \text{ m/s}^2). What would they weigh on Jupiter where gJ=24.8 m/s2g_J = 24.8 \text{ m/s}^2?
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