A pickup truck is traveling with a speed of 60 mph west At t

A pick-up truck is traveling with a speed of 60 mph west. At the moment the pick-up truck passes in front of you (while you\'re standing on the street), a person on the back of the truck throws a baseball with a speed of 40 mph east. If air resistance is ignored, from the driver\'s perspective, what is the velocity of the ball? A. 60 mph west B. 100 mph east C. 20 mph east D. 40 mph west E. none of the above

Which of the following would be categorized under Dynamics?

the compression of the meniscus in the knee

the result of the compression of the meniscus on the knee

ground reaction forces when standing

force production in a concentric contraction

grip strength measured on a hand grip dynanometer

Solution

observer is on the gorund hence velocity of ball wrt gorund , Vb = 40 mph

(east as +ve and west as -ve).

velocity of truck, Vt = 60 mph west = -60 mph

Velocity of ball wrt truck, Vbt = Vb - Vt = 40 - (-60)

= 40 + 60 = 100 mph

hence 100 mph east.

Ans(B)