Which of the following represents the equation of motion of a steel ball thrown into a viscous liquid when it is moving with an acceleration a ?(A) W-V-U=ma (B)W-U=ma-V (C)W-U-V=0 (D)U-V=W

A

Explanation: When a steel ball is thrown into a viscous liquid, three forces will act on the ball.

1.) The viscous drag force V which is acting upward

2.) The buoyant force U which is acting upward and

3.) The weight of the ball W. Which is acting downward.

When it is moving with an acceleration a, the weight W will be greater than U and V

Since Force = ma.

The resultant vector force will be

W - V - U = ma

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.