Inelastic collision causes loss of momentum. What are two physical reasons for the loss?

In physics lab we collided two objects that then both started moving in the same direction. We measured the velocities through two photo gates. We know momentum was lost because the velocities decreased after the collision. What are two physical reasons for the loss of momentum?

The Conservation of Energy

A skier coasts down a very smooth, 10-m-high slope (v =20 m/s), what is his speed at the bottom of the slope. If the skier has a mass of 60kg and the force of friction retards his motion by doing 2500 j of work, what is his speed at the bottom of the slope?

Work Done by Constant Force

A 500-kg helicopter ascends from the ground with an acceleration of 2.00m/s2. Over a 5.00-s interval, what is (a) the work done by lifting force, (b) the work done by the gravitaional force, and (c) the new work done on the helicopter?

Power

Water is lifted out of a well 30.0m deep by a motor rated at 1.00 hp. Assuming 90% efficiency, how many kilograms of water can be lifted in 1 minute?

Angular Measure

Assume that the Earth's orbit around the sun is circular. In kilometers, what is the approximate orbital distance the Earth travels in three months?

Uniform circular motion

A rotating cylinder about 16km in length and 8.0 km in diameter is designed to be used as a space colony. With what angular speed must it rotate so that the residents on it will experience the same acceleration due to gravity on Earth?

Uniform circular Motion

A car with a constant speed of 83.0 km/h enters a circular flat curve with a radius of curvature of .400 km. If the friction between the road and the car's tires can supply a centripetal acceleration of 1.25m/s^2, does the car negotiate the curve safely? Justify your answer.

Angular Acceleration

The blades of a fan running at low speed turn at 250 rpm. When the fan is switched to high speed, the rotation rate increases uniformly to 350 rpm in 5.75 s. a.) What is the magnitude of the angular acceleration of the blades? b.) How many revolutions do the blades go through while the fan is accelerating?

Newtons Law of Gravitation

A 75 kg man weighs 735 N on the Earth's surface. How far above the surface of the Earth would he have to go to "lose" 10% of his body weight?

energy and momentum of photon

An electron moving at a speed of 0.60c collides head on with a positron of speed at 0.60c. Determine the energy andmomentum of each photom produced in the process.