A meteorite falls, under the influence of Earth\'s gravitation, from rest at a h
ID: 1435038 • Letter: A
Question
A meteorite falls, under the influence of Earth's gravitation, from rest at a height of 630 km above the surface of Earth. What is its speed when it reaches the surface of the Earth. What is its speed when it reaches the surface of the Earth? A boy, initially at rest, swings across a 38 m wide stream on a 38m long rope attached to a limb hanging midway over the steam. The banks on both sides are the same distance above the water. The speed of the boy at his lowest point of the swing is: A 290 g baseball is thrown from a height of 2.0 m above the ground with a speed of 16 m/s and reaches the height of 9.0 m above the ground with a speed of 10.0 m/s. The work done against air drag is A 60 kg paratrooper falls straight downward at a constant speed of 4.0 m/s. The amount of work done by the air drag on the paratrooper as he falls 50 m is A 4.0 kg object moving initially at 5.0 m/s along a straight line on a smooth surface is pulled a distance of the object's motion. the final speed of the object is A crane can raise a 400 kg load to the top of a 60 m tall building in 36 s. The power expended by the crane isExplanation / Answer
1. 0.5mv^2 = mgh
v = 3513 m/s (A)
2. sin(theta) = 19/38
theta = 30 degree
h = 38 - 38cos(theta) = 5.09m
v = 9.98 m/s
3. energy lost = 0.5m*16^2 - mg*7 - 0.5m*10^2 = -2.72J
4. Acceleration is zero, so drag force = mg
work = -mg*50 = -29.4 kJ
5. Work done = 120J
0.5*4*5^2 + 120 = 0.5*4*v^2
v = 9.219 m/s
6. Power = 400*60/36 = 0.666 kW