A ball is thrown straight up. After t seconds its height is h = 30t - 5t² metres.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A ball is thrown straight up. After seconds its height is metres. When is the ball highest, how high does it go, and when does it come back to the ground?
Need a reminder? The key ideaShow
has its vertex at and opens upward when . Completing the square, , gives the vertex and the range.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The top. .
Step 2. The height. .
Step 3. Landing. at .
Answer: highest at , at ; back down at .
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