Your average speed is 20 mph, but ONLY IF YOU'RE IN THE CAR during those 2 hours.
The point in which it originates.
The rock strike the water with the speed of 15.78 m/sec.
The speed by which rock hit the water is calculated by the formula
v=
v=
v=15.78 m/sec
Hence, the rock strike the water with the speed of 15.78 m/sec.
All it does is lets him pull in a more convenient direction to raise the load. It has no effect on the required force.
When Janet leaves the platform, she's moving horizontally at 1.92 m/s. We assume that there's no air resistance, and gravity has no effect on horizontal motion. There's no horizontal force acting on Janet to make her move horizontally any faster or slower than 1.92 m/s.
She's in the air for 1.1 second before she hits the water.
Moving horizontally at 1.92 m/s for 1.1 second, she sails out away from the platform
(1.92 m/s) x (1.1 sec) = <em>2.112 meters</em>
