Mechanics | Relativity Answers

the length of a spring is spring is 16cm when a load of 5n is attached to the spring is 20n the length is 19cm .calculate th
(i) force constant of the spring
(ii)original length of spring

If I throw a photon into space, over time its energy will decrease because its wavelength is stretched by the expansion of space.
We canbthen ask ourselves "where is this lost energy going?" or this energy just disappear?

A mass of m is sliding on a inclined plane of mass M which is kept on smooth surface find displacement of mass M.

Two masses of 1 kg and 2 kg are moving with velocity 2m/s and 1m/s find the velocity of center of mass

A man of 30 kg walking on a plank of 100kg find the displacement of plank?

A tennis ball is dropped from 1.21 m above the ground. It rebounds to a height of 1.05 m. With what velocity does it hit the ground? The acceleration of gravity is 9.8 m/s 2 . (Let down be negative.) Answer in units of m/s.

With what velocity does it leave the ground? Answer in units of m/s

An engineer in a locomotive sees a car stuck on the track at a railroad crossing in front of the train. When the engineer first sees the car, the locomotive is 200 m from the crossing and its speed is 20 m/s. If the engineer’s reaction time is 0.49 s, what should be the magnitude of the minimum deceleration to avoid an accident? Answer in units of m/s 2 .

During a baseball game, a batter hits a high pop-up. If the ball remains in the air for 5.93 s, how high above the point where it hits the bat does it rise? Assume when it hits the ground it hits at exactly the level of the bat. The acceleration of gravity is 9.8 m/s 2 . Answer in units of m.

A planet has a mass of 5*10 24 kg and a radius of 6.1*10 6 m. Find the energy needed to lift a mass of 2.0 kg from its surface into outer space

Show that the period of a particle that moves in a circular orbit close to the surface of a sphere
depends only upon G and the average density ρ of the sphere. Find what this period would be
for any sphere having an average density equal to that of water.