Mechanics | Relativity Answers

why we take accelaration as accelaration due to gravity and not the average of accelaration due to motion of particles of fluid and accelaration due to gravity in finding the pressure of fluid at rest. in fluid at rest why we do not take the value of accelaration provided by motion of fluid particles.why?

Two spherical bodies of mass M and 5M and radii R and 2R respectively are released in free space with initial separation between their centres eual to 12R. If they attract each other due to gravitational force only , then the distance covered by the smaller body just before collision is
(1)2.5R
(2)4.5R
(3)7.5R
(4)1.5R

Water is pumped through a hose-pipe at a rate of 20 litres/mim and from the nozzle with the velocity 20 m/s. find the force of reaction on the nozzle in newton
and the usefull power of the pump in watt.

a train blowing its whistle moves with constant speed on a straight track towards observer and then crossed him.if the ratio of different between actua. and apparent frequency be 3:2 in two cases then the speed of train ...

the frequency change by 10% as a sound source approach a stationary observer with constant velocity V.what would be % change in the frequency as the source reduce the observer with same speed...

Q. find the radial and transverse components of a particle moving along the circle
square of x plus square of y is equal to square of a.

Q.show that on a hypothetical planet having half the diameter of the earth but twice its density, the acceleration of free fall is same as on earth.

considering no air resistance.suppose we throw a ball from the surface of the earth parellel to the ground,then after covering some distance in horizontal motion slowly the ball changes it's direction and falls in projectile motion on the surface of earth due to gravity.why does the ball do not fall vertically to the surface of the earth and instead it falls in projectile motion?why?how?

Lift
Lift on an aeroplane wing results from:

1. locally reaching the speed of sound in the boundary layer of the upper face of the aerofoil

2. a pressure difference between the faces of the aerofoil

3. a local increase in density at the upper face of the aerofoil

4. creating micro-vortices on the upper face which decrease the viscosity of the fluid

This question refers to: Laws of motion
A mass of 2 kg travelling at 2 m/s is struck by a mass of 4 kg travelling at 3 m/s. If the coefficient of restitution for the two materials is 0.4, calculate their final velocities.
Give the final velocity value in m/s of the 4kg mass