Which of the following cases is the object in free fall?
1. An object dropped from a certain height.
2. An object is thrown upward or an object thrown downwards from the top of a tower.
3. An object in the aircraft flying at constant speed.
4. An object in a car accelerating at 9.8 m/s2 on the road.
Which of the following cases is the object in free fall?
1. An object dropped from a certain height.
2. An object is thrown upward or an object thrown downwards from the top of a tower.
3. An object in the aircraft flying at constant speed.
4. An object in a car accelerating at 9.8 m/s2 on the road.
The correct option is C Only 1st and 2nd are in free fall
Free fall is any motion of a body where its weight is the only force acting upon it.
An object is in free fall even when moving upwards or instantaneously at rest at the top of its motion. If gravity is the only influence acting, then the acceleration is always downward and has the same magnitude for all bodies.
As per the definition of the free fall:
In 1st case, an object is moving downwards, due to its weight (gravitational force of attraction). There is no other force acting on it except its weight or gravitational force. So, it is a free fall.
In 2nd activity, an object is thrown upwards or downwards. While throwing the object, some external force is exerted on the object to make it move. But, once it is released the external force disappears and no force will act on it except its own weight. So, it is said to be in free fall.
In 3rd activity, the object in the aircraft is moving at a constant speed. I.e. it is not moving towards the Earth with an acceleration of 9.8m/s2. So, it is not in free fall.
In 4th activity, the car is accelerating at 9.8 m/s2 with the help of its engine power (force). Thus, the object in it is not at free fall. Since weight is not the only force acting on it.
Only 1st and 2nd are in free fall
Free fall is any motion of a body where its weight is the only force acting upon it.
An object is in free fall even when moving upwards or instantaneously at rest at the top of its motion. If gravity is the only influence acting, then the acceleration is always downward and has the same magnitude for all bodies.
As per the definition of the free fall:
In 1st case, an object is moving downwards, due to its weight (gravitational force of attraction). There is no other force acting on it except its weight or gravitational force. So, it is a free fall.
In 2nd activity, an object is thrown upwards or downwards. While throwing the object, some external force is exerted on the object to make it move. But, once it is released the external force disappears and no force will act on it except its own weight. So, it is said to be in free fall.
In 3rd activity, the object in the aircraft is moving at a constant speed. I.e. it is not moving towards the Earth with an acceleration of 9.8m/s2. So, it is not in free fall.
In 4th activity, the car is accelerating at 9.8 m/s2 with the help of its engine power (force). Thus, the object in it is not at free fall. Since weight is not the only force acting on it.
