power=energy/time=(1/2 mv^2)/5
change tonnes to kg
A truck of mass 2 tonnes moving at a speed of 25 m/s is brought to rest suddenly in 5 seconds. Calculate the power exerted by the brakes
3 answers
work done = loss of ke = (1/2)m v^2
= 1000*625 Joules
power = work/second
= 1000 * 625 / 5 Watts
= 1000*625 Joules
power = work/second
= 1000 * 625 / 5 Watts
A man claims that he can hold onto a 9.0-kg child in a head-on collision as long as he has his seat belt on. Consider this man in a collision in which he is in one of two identical cars each traveling toward the other at 49.0 mi/h relative to the ground. The car in which he rides is brought to rest in 0.05 s.
(a) Find the magnitude of the average force needed to hold onto the child.
(a) Find the magnitude of the average force needed to hold onto the child.