Question

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

Answer 1

Answer:

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