Mechanics | Relativity Answers

A ball of mass 0.05kg strikes a smooth wall normally 4 times in 2 seconds with a velocity of 10m/s. Each time the ball rebounds with the same speed of 10 m/s. Calculate the average force on the wall. Draw a sketch showing how the momentum varies with time over the 2 seconds.

A ball of mass 0.2kg falls from a height of 45m. On striking the ground, it rebounds in 0.1s with ⅔ of the velocity with which it struck the ground. Calculate (i) the momentum change on hitting the ground (ii) the force on the ball due to the impact

An astronaut is outside her space capsule in a region where the effect of gravity can be neglected. She uses a gas gun to move herself relative to the capsule. The gas gun fires gas from a muzzle of area 160 mm^2 at a speed of 150m/s. The density of the gas is 0.800kg/m^3 and the mass of the astronaut, including her spacesuit, is 130kg. Calculate (a) the mass of gas leaving the gun per second, (b) the acceleration of the astronaut due to the gun, assuming that the change in mass is negligible.

A body is acted upon by a force F which varies with time t. Sketch a graph which best represents the velocity (v)-time (t) variations of the body?

The sides of the triangle ABC represents 3 velocities AC(magnitude 3.6m/s) corresponds to the velocity of a boat as observed by a stationary tourist on a bridge. BC (magnitude 1.5m/s) corresponds to the velocity of a cyclist crossing the bridge, once again as seen by the tourist. Calculate the magnitude of the velocity vector AB, the velocity of the boat relative to the cyclist.

Projectiles containing delicate electronic equipment may be damaged if they are subjected to high accelerations. For this reason, such projectiles may be fired from guns with long barrels but not from guns with short barrels. (a) State 2 factors that affect the range of a projectile fired from a gun (b) Explain why a projectile fired from a long-barrelled gun is subject to less acceleration than a projectile fired from a short-barrelled gun if the range is the same in both cases. © Draw a free-body force diagram for a projectile just after it has left the barrel of a gun (L)

A small smooth object slides from rest down a smooth inclined plane inclined at 30 degrees to the horizontal. What is (i) the acceleration down the plane (ii) the time to reach the bottom if the plane is 5m long? The object is now thrown up the plane with an initial velocity of 15m/s. (iii) How long does the object take to come to rest? (iv) How far up the plane has the object then traveled?

A ball is dropped from a height of 20m and rebounds with a velocity which is ¾ of the velocity with which it hit the ground. What is the time interval between the first and second bounces?

A car moving with a velocity of 10 m/s accelerates uniformly at 1m/s2 until it reaches a velocity of 15 m/s. Calculate (i) the time taken (ii) the distance traveled during the acceleration (iii) the velocity reached 100m from the place where the acceleration began.

An aluminum ball X and an iron ball Y of the same volume are thrown horizontally with the same velocity from the top of a building. Neglecting air resistance, X reaches the ground (a) before Y and at the same distance from the building (b) at the same time as Y and at a nearer distance to the building (c) at the same time as Y and at the same distance from the building (d) at the same time as Y and further from the building (e) after Y and at the same distance from the building