A car whose mass is 1000 kg is travelling at a constant speed of 10ms-1. Neglecting any friction, how much force will the engine have to supply to keep going the same speed? F = ma Since it is travelling at a constant speed then acceleration = 0 ms-2 hence the answer is 0. F = m x a F = 1000 x 0 F = 0 My question is: Firstly am I right? And secondly why does everything have to be accelerating? If the car was travelling at a constant speed of 10ms-1 and there was friction how would you calculate the force needed?