Question

1 What is the Earth's orbital speed as it orbits the Sun. Take the Earth/Sun distance to be 93 million miles (taking the Earth's orbit to be circular), the mass of the Earth to be 5.97 X 102 kg and the mass of the Sun to be 1.987 X 10*0 kg. Solve this problem using Newton's 2nd law directly 2. A 55.7 kg mass is lifted (at a constant velocity) from the ground to a vertical height of 1275 m. How much work is done by gravity in lifting the mass to this height? The mass is then thrown with an initial speed of 25 m/s from that height and allowed to fall back to the ground. Using energy considerations, find the speed of the mass the instant before it strikes the ground 3. A 58kg skier coasts down a 25° slope. A kinetic frictional force of magnitude 70N opposes her motion. Near the top of the slope her speed was v- 3.6m/s. Ignoring air resistance, determine her speed at a point 57m downhill. 4. A 5.00 g bullet leaves the muzzle of a rifle with a speed of 320.015 m/s. What force (assumed constant) is exerted on the bullet while it is traveling down the 0.82 m long muzzle of the rifle, using work/energy methods? Using conservation of energy, find the velocity of the bullet just before it strikes the ground, if it is fired from a height of 5.0 m above the ground. 5. A open cart slides along a frictionless track. Rain falls vertically into the open cart thereby increasing its mass. As a result of the increasing mass, what happens to the kinetic energy of the cart? Explain your answer.

Answer 1

H= 1,987 X1030 kg γ= 93x106 ,mi los 1-49637メ10 2