A Question?

[Trisha Graal Emile]

1. A metal ball is dropped into a tall cylinder of oil. The ball initially accelerates but soon reaches a terminal velocity.
a. By considering the forces in the metal ball bearing, explain why it first accelerates but then reaches terminal velocity.
b. Describe how you would show that the metal ball reaches terminal velocity.

 

[acash09]

The ball keeps accelerating due to its weight, which is w=m.g , m being the mass of the ball and g the acceleration of free fall. When the resistive force to the motion of the ball due to the oil reaches a value that is equal to weight of the ball, there is no more acceleration and the ball now falls at a constant speed, called the terminal velocity.

Using a system of light sensors that are connected to an electronic timer or computer and some lasers, each kept at a constant distance from each other, could be used to measure the velocity at which the ball crosses the lasers and using the time and distance, the velocity at each segment is calculated. The smaller the segments, the more accurate the velocity value.

 

[aalmuhannadi]

Adding on to what acash09 said, you can prove that the ball reaches terminal velocity by looking at the recorded times. The time intervals will initially be greater>smaller>smaller until eventually at one point time intervals will be the same, meaning that the ball is now travelling the same distance in the same time period. This now proves it is at terminal velocity.

 

[fareha1]

In the battles fought by the caliphs..wot wot is necessary to include ?