Idea 4of 5Builds onAcross is steadyDown is free fall
One clock
Where do the two motions connect?
Today you'll discover
- the one thing the two motions share
- which motion decides the time
- the method every projectile problem uses
Think firstTwo motions, one landing time
What decides how long the fired ball is in the air?
Decide first, then press Next. Watch which motion the clock belongs to.
Both balls landing together. After a prediction, the brackets down the right show the fall taking 0.64 seconds, then the marks along the top show the sideways motion covering 1.9 metres in that same time. Then the curved path with the method named. The last step shows the cliff launch and asks which number to find first.
See the whole ideathe big idea and the key word, in one place
The big idea
The fall sets the time. The sideways motion spends it.
Where it goes nextThe bench in the lesson has a height slider and a speed slider. Move the speed: the flight time does not budge.
About this modelAir is ignored: the ball is drawn as it would move in a vacuum.
Air is ignored: the ball is drawn as it would move in a vacuum.
Ready to use it?
- Solve a horizontal launch: time from the height, distance from the speed.