In the following example, try to identify the number of times the velocity of the ball changes:
“A football player kicks a football to another player of his team who kicks the football towards the goal. The goalkeeper of the opposite team collects the football and kicks it towards a player of his own team”.
Also identify the agent supplying the force in each case.
The velocity of the ball changes four times. As a football player kicks the football, its speed changes from zero to a certain value. As a result, the velocity of the ball gets changed. In this case, the player applied a force to change the velocity of the ball. Another player kicks the ball towards the goal post. As a result, the direction of the ball gets changed.
Therefore, its velocity also changes. In this case, the player applied a force to change the velocity of the ball. The goalkeeper collects the ball. In other words, the ball comes to rest. Thus, its speed reduces to zero from a certain value. The velocity of the ball has changed. In this case, the goalkeeper applied an opposite force to stop/change the velocity of the ball. The goalkeeper kicks the ball towards his team players. Hence, the speed of the ball increases from zero to a certain value. Hence, its velocity changes once again. In this case, the goalkeeper applied a force to change the velocity of the ball.
An automobile vehicle has a mass of $1500\, kg$. What must be the force(in $N$) between the vehicle and road if the vehicle is to be stopped with a negative acceleration of $1.7\, m \,s^{-2}$ ?
Explain, why is it difficult for a fireman to hold a hose, which ejects large amounts of water at a high velocity.
A truck starts from rest and rolls down a hill with a constant acceleration. It travels a distance of $400 \,m $ in $20\, s$. Find the force(in $N$) acting on it if its mass is $7$ tonnes ($1$ tonne $= 1000\, kg$)
A hockey ball of mass $200 \,g $ travelling at $10 \,m \,s^{-1}$ is struck by a hockey stick so as to return it along its original path with a velocity at $5 \,m\, s^{-1}$. Calculate the magnitude of change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick.
A batsman hits a cricket ball which then rolls on a level ground. After covering a short distance, the ball comes to rest. The ball slows to a stop because