Impulse equals change in momentum. If a 1.0 kg object experiences a 8 N force for 0.5 s, what is the resulting change in velocity? (Assume initial velocity is zero.)

Impulse equals change in momentum. If a 1.0 kg object experiences a 8 N force for 0.5 s, what is the resulting change in velocity? (Assume initial velocity is zero.)

• A. 2 m/s
• B. 4 m/s
• C. 8 m/s
• D. 6 m/s

Answer: (B)

Impulse is the change in momentum, and for a constant force impulse equals force times time: J = F Δt. Here that gives J = 8 N × 0.5 s = 4 N·s, which is the change in momentum Δp. With a mass of 1 kg, Δp = m Δv, so Δv = Δp / m = 4 kg·m/s ÷ 1 kg = 4 m/s. Since the initial velocity is zero, the resulting change in velocity is 4 m/s.

Impulse is the change in momentum, and for a constant force impulse equals force times time: J = F Δt. Here that gives J = 8 N × 0.5 s = 4 N·s, which is the change in momentum Δp. With a mass of 1 kg, Δp = m Δv, so Δv = Δp / m = 4 kg·m/s ÷ 1 kg = 4 m/s. Since the initial velocity is zero, the resulting change in velocity is 4 m/s.