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.
Let the two football teams be team A and team B, respectively. Initially, the football is at rest. Now, the football is kicked by a player of team A to another player of team A. (The velocity of the ball has changed 1 time so far). This change is brought on by the force applied by the player who kicked the ball.
The football is now kicked by the other team, A player, towards the goal. (The velocity of the ball has changed 2 times so far). This change is also brought on due to the force applied by the team, A player who kicked the ball.
The goalkeeper of team B stops the ball, bringing it to rest. (the velocity of the ball has changed 3 times so far). This change is brought on by the force applied by the goalkeeper of team B to stop the ball.
Finally, the goalkeeper of team B kicks the ball towards another player of team B. the velocity of the ball changes for a final time, bringing the total count to 4. This change is also brought on by the goalkeeper of team B, who applies the force to kick the ball forward.
Therefore, the velocity of the ball changes 4 times in this example.Answered by Shivani Kumari | 1 year ago
A motorcar of mass 1200 kg is moving along a straight line with a uniform velocity of 90 km/h. Its velocity is slowed down to 18 km/h in 4 s by an unbalanced external force. Calculate the acceleration and change in momentum. Also calculate the magnitude of the force required
Two persons manage to push a motorcar of mass 1200 kg at a uniform velocity along a level road. The same motorcar can be pushed by three persons to produce an acceleration of 0.2 m s-2. With what force does each person push the motorcar? (Assume that all persons push the motorcar with the same muscular effort)
The following is the distance-time table of an object in motion:
|Time (seconds)||Distance (meters)|
(a) What conclusion can you draw about the acceleration? Is it constant, increasing, decreasing, or zero?
(b) What do you infer about the forces acting on the object?