An object weighs 8000 N on Earth, using g ≈ 10 m/s^2. What is its mass?

An object weighs 8000 N on Earth, using g ≈ 10 m/s^2. What is its mass?

• A. 80 kg
• B. 800 kg
• C. 400 kg
• D. 1000 kg

Answer: (B)

Weight is the gravitational force on an object and equals mass times gravity: W = m g. You're given a weight of 8000 N and use g ≈ 10 m/s^2. Solve for mass: m = W / g = 8000 N / 10 m/s^2 = 800 kg. So the object’s mass is about 800 kilograms. If you check the other masses, they wouldn’t give 8000 N with that gravity: 80 kg would weigh about 800 N, 400 kg about 4000 N, and 1000 kg about 10000 N. Using 9.8 m/s^2 would give m ≈ 8000 / 9.8 ≈ 816 kg, but with the given g, 800 kg is the correct result.

Weight is the gravitational force on an object and equals mass times gravity: W = m g. You're given a weight of 8000 N and use g ≈ 10 m/s^2. Solve for mass: m = W / g = 8000 N / 10 m/s^2 = 800 kg. So the object’s mass is about 800 kilograms. If you check the other masses, they wouldn’t give 8000 N with that gravity: 80 kg would weigh about 800 N, 400 kg about 4000 N, and 1000 kg about 10000 N. Using 9.8 m/s^2 would give m ≈ 8000 / 9.8 ≈ 816 kg, but with the given g, 800 kg is the correct result.