Question

An advertisement claims that a certain 1200 kg car can accelerate from rest to a speed of 25 m/s in a time of 8s. What average power must the motor produce to cause this acceleration? (Ignore friction losses)

• A. 46.9 kW
• B. 56.9 kW
• C. 76.9 kW
• D. Zero

Answer 1

The correct option is A 46.9 kW

$W=\Delta K=\frac{1}{2}m(v_f^2-v_i^2)=\frac{1}{2}\left(1200\right)\left[\right(25{)}^2-0]orW=375KJPower=\frac{w}{t}=\frac{375}{8}=46.9kW$