9. A force does 50) of work on an object at rest with a mass of 4 kg. Which of the following is the final velocity of the object?

25 m/s

5 m/s

3.5 m/s

5 m/s

Explanation:

Work is force times distance.

W = Fd

Force is mass times acceleration.

W = ma d

Acceleration is change in velocity over change in time.

W = m Δv / Δt d

Distance over time is average velocity.

W = m Δv v_avg

W = m (v - v₀) (v + v₀) / 2

W = m (v² - v₀²) / 2

Plugging in values:

50 J = 4 kg (v² - (0 m/s) ²) / 2

25 m²/s² = v²

v = 5 m/s