Question

On a foggy day, you are driving at 70 mph and Granny is driving at 50 mph. As you try to pass her, you both see an overturned truck and simultaneously slam on your brakes. Assume that both vehicles are identical and that Granny stops just before the truck. Approximately how fast are you traveling when you hit the truck?

Answer 1

Answer:

20 mph

Explanation:

Granny stopped from 50mph,

Her deceleration per unit time is

a = 50 - 0 = 50m/hr^2

This is also the amount of deceleration you experience per unit time (because both cars are identical), therefore your final speed with which you collide with the truck will be,

50 = 70 - v

V = 70 - 50 = 20mph