A 2 kg block is initially at rest on a rough horizontal surface with coefficient of friction 0.5. A force F varies with time as shown in the graph. Find the speed of the block at t = 4 s.

Question

G1 Physics · Accepted Answer

From the graph F = 5t N. Maximum friction is μmg = 0.5×2×10 = 10 N, so motion starts at t = 2 s. For t > 2 s, a = (5t-10)/2. Hence v(4) = ∫₂⁴(5t-10)/2 dt = 5 m s⁻¹.