A car travelling at a speed of 72 km/h is uniformly retarded by an applicationof brakes and comes to rest after 8 seconds. If the car with its occupants has a mass of 1,250 kg. Calculate;
a) The breaking force
b) The work done in bringing it to rest
A force of 7.5 N stretches a certain spring by 5 cm. How much work is done in stretching this spring by 8.0 cm?
A girl of mass 50 kg walks up a flight of 12 steps. If each step is 30 cm high, calculate the work done by the girl climbing the stairs
Calculate the work done by a stone mason lifting a stone of mass 15 kg through a height of 2.0 m. (take g=10N/kg)
A wooden box of mass 30 kg rests on a rough floor. The coefficient of friction between the floor and the box is 0.6. Calculate
a) The force required to just move the box
b) If a force of 200 N is applied the box with what acceleration will it move?
A block of metal with a mass of 20 kg requires a horizontal force of 50 N to pull it with uniform velocity along a horizontal surface.
Calculate the coefficient of friction between the surface and the block. (take g = 10 m/s)
A box of mass 50 kg is dragged on a horizontal floor by means of a rope tied to its front.
If the coefficient of kinetic friction between the floor and the box is 0.30, what is the force required to move the box at uniform speed?
A minibus of mass 1,500 kg travelling at a constant velocity of 72 km/h collides head-on with a stationary car of mass 900 kg.
The impact takes 2 seconds before the two move together at a constant velocity for 20 seconds.
Calculate
a) The common velocity
b) The distance moved after the impact
c) The impulsive force
d) The change in kinetic energy
A resultant force of 12 N acts on a body of mass 2 kg for 10 seconds.
What is the change in momentum of the body?
A bullet of mass 0.005 kg is fired from a gun of mass 0.5 kg.
If the muzzle velocity of the bullet is 300 m/s, determine the recoil velocity of the gun.
