Physics Projectile Motion

Question

A car is parked on a cliff overlooking the ocean on an incline that makes an angle of 17 degrees below the horizontal. The negligent driver leaves the car in neutral, and the emergency brakes are defective. The car rolls from rest down the incline with a constant acceleration of 4.8 m/s 2 and travels 43 m to the edge of the cliff. The cliff is 30 m above the ocean. (a)How long is the car in the air? The acceleration of gravity is 9.81 m/s 2 . Answer in units of s.

(b) What is the car’s position relative to the base of the cliff when the car lands in the ocean? Answer in units of m.

Answer 1

A car is parked on a cliff overlooking the ocean on an incline that makes an angle of 17 degrees below the horizontal. The negligent driver leaves the car in neutral, and the emergency brakes are defective. The car rolls from rest down the incline with a constant acceleration of 4.8 m/s 2 and travels 43 m to the edge of the cliff. The cliff is 30 m above the ocean. (a)How long is the car in the air? The acceleration of gravity is 9.81 m/s 2 . Answer in units of s

Speed of car after 43 m

V² = U² +2aS

U = 0

V= sqrt 412.8 = 20.32 m/s

This speed has two components V Cos 17 ( Horizontal) and V Sin 17 ( Vertically down)

Using S = ut +1/2 at² For vertical

30 = ( V Sin17 )t +1/2 gt² Eq 1

And 30Cos17 = Horizontal distance

Speed = V Cos 17

Speed = Distance /time

20.32 Cos 17= 30 Cos 17 /t .... Eq 2

Use g= 9.81 and solve for t