At a fun fair, a contestant throws a ball horizontally

Question

At a fun fair, a contestant throws a ball horizontally, aiming to hit a coconut on a stand. The coconut is 4.0m in front of the contestant, and is 40cm below their arm's level. How fast must they throw the ball to hit the coconut? g=9.8ms^-2

Answer 1

At a fun fair, a contestant throws a ball horizontally, aiming to hit a coconut on a stand. The coconut is 4.0m in front of the contestant, and is 40cm below their arm's level. How fast must they throw the ball to hit the coconut? g=9.8ms^-2

Strategy: Split up the x and y components of motion and use the fact that they travel for the same amount of time.

Velocity = < x , 0y >

V_o = √x² = x ( velocity only has an x component at t = 0 )

Find time using the Δy

Δy = V_ot + 1/2 a t²

√(2Δy / a) = t

√(2*-0.4m/-9.8m/s²) = t

0.286 s = t

Use: Δx = V_o t + 1/2 a t²

4m = V_o (0.29s)

V_o = 13.8 m/s