Which of the following actions are in free fall?
1. An object dropped from a certain height.
2. An object is thrown upward or a person jumping off.
3. Flying in an aircraft.
4. A car accelerating at 9.8 ms−2 on the road.
Which of the following actions are in free fall?
1. An object dropped from a certain height.
2. An object is thrown upward or a person jumping off.
3. Flying in an aircraft.
4. A car accelerating at 9.8 ms−2 on the road.
The correct option is C Only 1st and 2nd are in free fall
Freefall is any motion of a body where its weight is the only force acting upon it. Technically, 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 the 1st activity, 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 the 2nd activity, an object is thrown upwards. While throwing the object, some external force will be exerted on the object to make it move upwards, but once it is released into the air, the external force disappears and no force will act on it except its own weight (which is the gravitational force exerted on the object by earth). So, it is said to be in free fall.
In the 3rd activity, aircraft will move horizontally or vertically due to its engine power (force). So, there will be other forces acting on it to move it upwards or downwards accordingly. Since weight is not the only force acting on it. It is not in free fall.
In the 4th activity, the car is accelerating at 9.8 ms−2 with the help of its engine power (force). Thus, it is not a free fall. Since weight is not the only force acting on it.
Only 1st and 2nd are in free fall
Freefall is any motion of a body where its weight is the only force acting upon it. Technically, 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 the 1st activity, 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 the 2nd activity, an object is thrown upwards. While throwing the object, some external force will be exerted on the object to make it move upwards, but once it is released into the air, the external force disappears and no force will act on it except its own weight (which is the gravitational force exerted on the object by earth). So, it is said to be in free fall.
In the 3rd activity, aircraft will move horizontally or vertically due to its engine power (force). So, there will be other forces acting on it to move it upwards or downwards accordingly. Since weight is not the only force acting on it. It is not in free fall.
In the 4th activity, the car is accelerating at 9.8 ms−2 with the help of its engine power (force). Thus, it is not a free fall. Since weight is not the only force acting on it.
