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5/40 MCQs for:

Dynamics: Newton’s Laws of Motion

A stone is thrown straight up. At the top of its path, the net force acting on it is:

Instantaneously equal to zero.

Greater than its weight.

Greater than zero, but less than its weight.

Equal to its weight.

An object of mass m sits on a flat table. The Earth pulls on this object with force mg, which we will call the action force. What is the reaction force?

The table pushing down on the floor with force mg.

The table pushing up on the object with force mg.

The object pushing down on the table with force mg.

The object pulling upward on the Earth with force mg.

A ripe mango falls from a tree 32 m tall. If its initial velocity is zero, the time it takes to reach the ground is:

64.0 s.

6.4 s.

1.8 s.

2.5 s.

When the rocket engines on the starship NO-PAIN-NO-GAIN are suddenly turned off, while traveling in empty space, the starship will:

Stop immediately.

Slowly slow down, and then stop.

Move with constant speed.

Go faster and faster.

A stack of books rests on a level frictionless surface. A force F acts on the stack, and it accelerates at 3.0 m/s². A 1.0 kg book is then added to the stack. The same force is applied, and now the stack accelerates at 2.0 m/s². What was the mass of the original stack?

3.0 kg.

2.0 kg.

None of the above.

1.0 kg.