HC Verma Chapter 8 Problem 1

Given / Data

Block 5 kg from rest moves 10 m on frictionless surface under 20 N. Find final speed.

Concept / Formula

Work-energy theorem: W_net=DeltaKE. Starting from rest: KE_i=0.

Step-by-step Solution

W=20*10=200 J. W_net=200 J. 200=0.5*5*v^2 -> v^2=80 -> v=4sqrt(5) approx 8.94 m/s.

Key Equations

W=Fd | W_net=0.5mv_f^2 – 0.5mv_i^2

Final Answer

v = 4sqrt(5) approx 8.94 m/s.

Common Mistakes

Forgetting KE_i=0; applying W=Fd when F is not parallel to d.

Quick Tip

Work-energy theorem is faster than Newton laws for finding speed after a displacement.