Question

The work done by a force on body of mass 5 kg to accelerate it in the direction of force from rest to 20 m/s2 in 10 second is

• A. 2x103 J
• B. 4x103 J
• C. 10-3 J
• D. 103 J

Answer 1

Answer: (D)

103 J

Answer 2

acceleration = $\frac {final \ velocity - initial \ velocity}{time}$
acceleration = $\frac {20 -0}{10}$= 2 m/s².
Force = mass × acceleration.
Given that the mass is 5 kg and the acceleration is 2 m/s²:
Force = 5 kg × 2 m/s² = 10 N.
Work = Force × Displacement × cos(θ).
Displacement = $\frac {1}{2}$ × acceleration × time²
Displacement = $\frac {1}{2}$ × 2 m/s² × (10 s)² = 100 m.
Work = 10 N × 100 m × 1 = 1000 J.
Therefore, the work done by the force is 1000 Joules (J).
The correct option is (D) 103 J.