A student used a video camera to record another student dropping a marble through water in a graduated cylinder. The students watched the video in slow motion and made the observations shown below.
During which part or parts of the marble's fall did the marble experience unbalanced forces?
(1) Part A only
(2) Parts A and B only
(3) Part C only
(4) Parts B and C only
Answers
In part A, the only force is gravitational and so it falls downwards. In part B, buoyant force tries to compensate gravitational force and so speed decreases, even though it falls downwards which means the force is unbalanced. So, 2 is the answer.
Answer:
Part B and C only
Explanation:
A force is a push or pull (interaction) that changes the momentum of an object, either stationary or in motion when unopposed. All objects experience different forces depending on their environment. When immersed in fluids, unbalanced forces of one upward moving force tends to cancel the gravity force moving downward on a sinking object causing deceleration to a constant sinking speed. This upward moving force is called the Buoyant force. This is where at part A, the object experiences a balanced force of gravity that accelerates due to the absence of an opposing force acting upwards on the object. At part B, the speed of the sinking object decreases due to an unbalanced force that cancels the acceleration by the buoyant force. Once the sinking object’s acceleration is cancelled, its sinking speed turns constant (part C).