Final answer:
Speeding up going forwards at a non-constant rate is referred to as acceleration, which is the rate of change of velocity. A car taking a turn at a constant speed or a ship decelerating in the direction of motion are both examples of scenarios involving acceleration. Speeding up and slowing down can result from acceleration, illustrating that it is not merely about the increase in speed but any change in velocity.
Step-by-step explanation:
When we describe an object speeding up going forwards at a non-constant rate, we are talking about acceleration. Acceleration occurs when there is a change in an object's velocity, including when it speeds up, slows down, or changes direction. It is important to note that acceleration is not solely about an increase in speed; it's about changes in the speed or direction of motion. For example, a car that maintains a constant speed while taking a turn is experiencing acceleration due to the change in direction, even though its speed remains unchanged.
If a car goes over the top of a hill at a speed higher than the critical speed needed to maintain contact with the road, it may leave the road surface due to insufficient centripetal force. Alternatively, if the car goes over the top at slower than this critical speed, it will remain in contact with the surface. In both scenarios, acceleration is at play, but the outcomes are quite different.
In physics, we also clarify that acceleration in the same direction of motion results in speeding up, whereas acceleration in the opposite direction of motion causes an object to slow down. This distinction is exemplified by a ship moving forward at a steady rate, then decelerating in the forward direction—first slowing down with a higher rate of deceleration, and then continuing to slow down but with less deceleration. Both are cases of acceleration affecting the object's velocity.