Which of the following statement must always be true?
I.If an objects acceleration is zero, then its speed must remain constant.
II. If an objects acceleration is constant, then it must move in a straight line.
III. If an objects speed remains constant, then its acceleration must be zero.
Which of the following statement is false?
1. If speed is zero , it's velocity also must be zero.
2. if velocity is zero , then it's speed need not be zero
3. If speed is constant , then it's speed must be constant .
4. If velocity is constant , then it's speed must be constant.
Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her? Why?