You are traveling in a convertible with the top down. The car is moving at a con
ID: 1590880 • Letter: Y
Question
You are traveling in a convertible with the top down. The car is moving at a constant velocity 24.7 m/s, due east along flat ground. You throw a tomato straight upward at a speed of 12.3 m/s. How far has the car moved when you get a chance to catch the tomato? m
A swimmer, capable of swimming at a speed of 1.2 m/s in still water (i.e., the swimmer can swim with a speed of 1.2 m/s relative to the water), starts to swim directly across a 2.4-km-wide river. However, the current is 0.91 m/s, and it carries the swimmer downstream.
(a) How long does it take the swimmer to cross the river?
s
(b) How far downstream will the swimmer be upon reaching the other side of the river?
m
Explanation / Answer
part 1:
let after time t seconds you will catch the tomato.
initial horizontal speed of tomato=speed of the car at the time of throwing=24.7 m/s
as there is no horizontal acceleration, horizontal speed will remain constant
initial vertical speed is 12.3 m/s
if we take vertically upward direction as positive , then acceleration due to gravity will be -9.8 m/s^2
time taken by the tomato to reach on the same height as the car will be given by
2*initial vertical speed/acceleration due to gravity
=2*12.3/9.8=2.51 seconds
so after 2.51 seconds, the tomato will be caught
within that time period, the car will have moved a distance of speed*time
=24.7*2.51=62 meters
part 2:
speed of the swimmer in still water=u=1.2 m/s
speed of the current in the river=v=0.81 m/s
distance to be travelled directly across the river=2.4 km=2400 m
speed of the swimmer in that direction=1.2 m/s
then time taken=distance/speed
=2400/1.2=2000 seconds
part b:
in that 2000 seconds, the current would have moved the swimmer downstream by a distance of speed*time=0.91*2000=1820 m=1.82 km
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