A race car skidding out of control manages to slow down to 122.4 km/h before cra
ID: 1588335 • Letter: A
Question
A race car skidding out of control manages to slow down to 122.4 km/h before crashing head-on into a brick wall. Fortunately, the driver is wearing a safety harness. Using m for the mass of the driver and x for the stopping distance, find an equation for the average force (in Newtons) exerted on the driver by the safety harness, including its direction (the race car's direction of motion prior to the collision is the positive direction). Neglect any effects of frictional forces on the driver by the seat. (Remember to convert from km/h to m/s. Use any variable or symbol stated above as necessary.)
Explanation / Answer
Ans: The speed of car before collision is v= 122.4 km/h =(122.4*1000)/(3600) m/sec=34 m/sec.
Now the Kinetic energy of the driver is KE=0.5*m*v^2 , Say the Force given by the safety harness is F . Then the work done by the safety harness in stopping the driver is W =F * x . And since there is no friction So,
E= W ; or F= KE/x = 578*(m/x);