Newton's First Law

1.3. Which of Newton’s Laws is sometimes referred to as the Law of Inertia?
Newton's First Law

2. A bus is moving at a constant velocity of 12ms^-1. The driver presses the brakes sharply.
2.1. What would happen to a standing passenger if he was not holding on to the rails?
The passenger would continue moving at 12ms^-1 as a result of his own INERTIA.
Since the bus is now moving slower, he would collide with the inside of the bus.
He would appear to fall forward.

2.2. Why should he be holding on to the rails?
He would be able to "receive" a resultant force too, and this force would overcome his inertia.
He would be able to slow down as well.

3. A rocket traveling in space, reaches a maximum velocity of 12 000kmh^-1 and the captain then switches off the engines.
3.1. What would happen to the velocity of the rocket?
The velocity of the rocket would remain at 12 000kmh^-1 as result of its inertia.
There are no forces such as friction to overcome this inertia, so inertia maintains the velocity.

3.2. If a car reaches a maximum velocity of 60kmh^-1 on the road, and the driver switches off the engine, would the result be the same as in the case of the rocket? Explain.
No, the inertia of the car would be overcome by the friction forces the car would experience. Hence the car would slow down.

4. The pot-plant is placed on the table.

6.2. table cloth is pulled out fast?
The friction force would not have sufficient time to form a grip on the pot-plant.
Hence the inertia of the pot-plant would NOT be overcome.
The pot-plant would remain at rest, while the table cloth would be pulled out from underneath it.