Leaping the River?

Question

A car of weight 1.0000×10^4 N car comes to a bridge during a storm and finds the bridge washed out. The driver of weight 650 N must get to the other side, so the crazy bastard decides to try leaping it with his car. The side the car is on is 19.5 m above the river, while the opposite side is a mere 1.60 mabove the river. The river itself is a raging torrent 60.0 m wide.

How fast should the car be traveling just as it leaves the cliff in order just to clear the river and land safely on the opposite side? (Take the free fall acceleration to be g = 9.80 m/s^2)

What is the speed of the car just before it lands safely on the other side? (Take the free fall acceleration to be g = 9.80 m/s^2)

Answer 1

for the Dukes of Hazard to make it to the other side, the horizontal flight time must equal the free fall time

The free fall time is
19.5-1.6=9.8*t^2
t=1.35 seconds

the horizontal flight time is
v*t=60.0
v=60.0/1.35
v=44.4 m/s
actually v>44.4 m/s

Before the car lands it will have a magnitude of speed
sqrt(44.4^2+2*9.8*(19.5-1.6))

=48.2 m/s

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