Yes, forces can cause a change in the motion of an object, but specifically, it is an unbalanced force that is required to do so.
Understanding Force and Motion
A force is a push or a pull that can cause an object to accelerate. Acceleration means a change in velocity, which can involve changing speed, changing direction, or both.
According to the reference:
In order to change the motion of the object, an unbalanced force has to be applied to the body so that the body will have acceleration in the direction of the applied force. Thus, a force that causes an object to change its motion is called an unbalanced force.
This highlights a key concept in physics: for an object's motion to change (i.e., to accelerate), the net force acting on it must not be zero.
Balanced vs. Unbalanced Forces
Forces can be categorized as either balanced or unbalanced:
- Balanced Forces: When multiple forces act on an object and their effects cancel each other out, they are called balanced forces. The net force is zero. Balanced forces do not cause a change in motion. If an object is at rest, it stays at rest. If it is moving at a constant velocity (constant speed and direction), it continues to do so.
- Unbalanced Forces: When the forces acting on an object do not cancel each other out, there is a net force greater than zero. These are unbalanced forces. Unbalanced forces always cause a change in the object's motion, resulting in acceleration.
How Unbalanced Forces Change Motion
An unbalanced force alters an object's state of motion in several ways:
- Starting Motion: An unbalanced force can make a stationary object start moving.
- Changing Speed: An unbalanced force can make a moving object speed up or slow down.
- Changing Direction: An unbalanced force can make a moving object change its direction.
- Stopping Motion: An unbalanced force (like friction) can make a moving object stop.
Examples:
- Pushing a swing causes it to start moving (from rest).
- Pressing the accelerator pedal in a car causes it to speed up.
- Turning the steering wheel applies a force that changes the car's direction.
- Applying the brakes uses friction to slow a bicycle down.
In each of these cases, an unbalanced force is acting on the object, causing it to accelerate and change its motion.
