AI Tutor
Imagine rolling a tennis ball straight across a smooth gym floor, and a friend gives it a gentle kick from the side as it passes.
The ball does not simply speed up or stop — it immediately swerves onto a completely new path.
To understand why it turns, let's first look at what happens when forces push directly in a straight line.

Forces in a Straight Line

When a push acts along the exact same line an object is moving, only its speed changes.
Pushing directly from behind makes it speed up, while pushing directly from the front slows it down.
Straight pushes only change speed — but what happens when a push comes from the side?

The Angled Push

In 1687, English scientist Isaac Newton showed that moving objects keep traveling in a straight line unless an unbalanced force acts on them.
An unbalanced force is a push or pull that is not canceled out by an equal opposite force, causing an object to change its motion.
When a force strikes at an angle to the direction of travel, the object blends its original forward motion with the new sideways push.