Mechanics questions | form five Physics

1. Why does the kinetic energy of an earth satellite change in the elliptical orbit?
2. Give two factors which determine whether a planet has an atmosphere or not.

Answer / Solution

UNSOLVED

A spacecraft is launched from the earth to the moon. If the mass of the earth is 81 times that of the moon and the distance from the centre of the earth to that of the moon is about 4.0×10​^5​ km;

1. Draw a sketch showing how the gravitational force on the spacecraft varies during its journey.
2. Calculate the distance from the centre of the earth where the resultant gravitational force becomes zero.

Answer / Solution

UNSOLVED

1. Justify the statement that ‘If no external torque acts on a body, its angular velocity will not be conserved’.
2. A car is moving with a speed of 30 ms​^-1 on a circular track of radius 500m. If its speed is increasing at the rate of 2ms^​-2​ ; find its resultant linear  acceleration.

Answer / Solution

UNSOLVED

An object of mass 1kg is attached to the lower end of a string 1m long whose upper end is fixed and made to rotate in a horizontal circle of radius 0.6m. If the circular speed of the mass is constant, find the;

1. Tension in the string.
2. Period of motion.

Answer / Solution

UNSOLVED

A 75kg hunter fires a bullet of mass 10g with a velocity of 400ms​^-1 from a gun of mass 5kg. Calculate the;

1. Recoil velocity of the gun.
2. Velocity acquired by the hunter during firing.

Answer / Solution

UNSOLVED