Up and down

The idea

An object thrown vertically upward moves in a straight line, slows down, stops momentarily at the top, then falls straight down with increasing speed; motion in a vertical direction under gravity is vertical motion.

At the top

A ball is thrown straight up into the air.

What do you think the ball does at the very top of its path?

• Stops for a moment
• Keeps moving up
• Speeds up

Follow the ball

Slide the time from start to end. Watch the ball and the arrow.

Slow, stop, speed up

While going up, the ball slowed down. At the top it stopped for a moment and its direction changed. Coming down, it sped up.

An object thrown vertically upward moves in a straight line, slows down, stops momentarily at the top, and then falls straight down with increasing speed. Motion in a vertical direction under gravity is vertical motion.

• Part of the motion | Direction | Speed
• Going up | Up | Decreasing
• At the top | Changes | Zero for a moment
• Coming down | Down | Increasing

Notes

A ball thrown vertically up slows down, stops momentarily at the top, then falls with increasing speed. This is vertical motion.

Check yourself

A ball is thrown straight up. While it goes up, its speed …

At the top of its path, the ball …

While the ball is coming down, its speed …

Motion in a vertical direction under gravity is called …

• keeps increasing. Going up, the ball slows down.
• keeps decreasing — correct. Yes!
• stays the same. The speed keeps decreasing while it goes up.
• keeps moving up for ever. It stops momentarily at the top.
• moves sideways. It moves in a straight vertical line.
• stops for a moment — correct. Yes!
• keeps increasing — correct. Yes!
• keeps decreasing. Coming down, the speed keeps increasing.
• is zero. It is zero only for a moment at the top.
• circular motion. Vertical means straight up or down.
• vertical motion — correct. Yes!
• sideways motion. Vertical means straight up or down.