Name the principal on which a rocket works

1. An object moves along the x axis according to the equation x = 3.00t2 - 2.00t + 3.00, where x is in meters and t is in seconds. Determine (a) the average speed between t = 2.00 s and t = 3.00 s, (b) the instantaneous speed at t = 2.

A fire hose is turned on the door of a burning building in order to knock the door down. This requires a force of 1000 N.

A dancer starts 3 meters from the curtain then moves 8 meters from the curtain in 15 seconds. What was his velocity?

How many joules are needed each day

Consider an electric motor with a shaft power output of 22.5 kW and an efficiency of 85%. Determine the rate at which the motor dissipates heat to the room it is in when the motor operates at full load. In winter, this room is normally heated by a 2.

Total energy input is 1400 and my efficiency is 80% so what is the useful energy output in jules?

What is the force of gravity acting on a 2000-kg spacecraft when it orbits two Earth radii from the Earth's center (that is a distance r=6380 km above the Earth's Surface. The mass of the Earth is 5.98 x 1024 kg.

An LC circuit has a 6.00 mH inductor. The current has its maximum value of 0.570 A at t = 0s. A short time later the capacitor reaches its maximum potential difference of 66.0 V. What is the value of the capacitance?

The first law of thermodynamics states that ΔE = Q - W. Is this also a statement of the principle of conservation of energy? Yes, the heat added and the change in internal energy of the gas equal the work done by the piston.

How can we calculate the density of a sustance that has irregular volume