Question

A 1200 kg car reaches the top of a 100 m high hill at A with a speed vA. What is the value of vA that will allow the car to coast in neutral so as to just reach the top of the 150 m high hill at B with vB = 0? Neglect friction.

Answer 1

the value of vA that will allow the car to coast in neutral so as to just reach the top of the 150 m high hill at B with vB = 0 is 31.3 m/s

Step-by-step explanation:

given information

car's mass, m = 1200 kg

`h_(A)` = 100 m

`v_(A)` =
`v_(A)`

`h_(B)` = 150 m

`v_(B)` = 0

according to conservative energy

the distance from point A to B, h = 150 m - 100 m = 50 m

the initial speed
`v_(A)`

final speed
`v_(B)` = 0

thus,

`v_(B)`² =
`v_(A)`² - 2 g h

0 =
`v_(A)`² - 2 g h

`v_(A)`² = 2 g h

`v_(A)` = √2 g h

= √2 (9.8) (50)

= 31.3 m/s