Question

It has been said that in his youth George Washington threw a silver dollar across a river. Assuming that the wide, (a) what minimum initial speed river was 75 m was necessary to get the coin across the river and b) how long was the coin in flight?

Answer 1

A and B

Step-by-step explanation:

Answer 2

(a) 27.1 m/s

(b) 3.9 second

Step-by-step explanation:

Let the speed is u.

Maximum horizontal range, R = 75 m

The range is maximum when the angle of projection is 45°.

(a) Use the formula for the maximum horizontal range

`R=(u^(2))/(g)`

`75=(u^(2))/(9.8)`

u = 27.1 m/s

(b) Let the time of flight is T.

Use the formula for the time of flight

`T=(2uSin\theta)/(g)`

`T=(2* 27.1 * Sin45)/(9.8)`

T = 3.9 second