Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
A ball is dropped from a tower 80 m high. Use . Make a table for the times 0, 0.5, 1, ..., 4 seconds with the speed and the height above the ground . Is the ball still in the air at 4 s? How long does it take to reach the ground?
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.
Plan. Put the times in an array. The speed and the height are two formulas on the whole array. The fall time comes from : , so .
Check. At 2 s the ball has fallen m, so the height is 60.4 m. At 4 s it has fallen 78.4 m, so the height is 1.6 m and it is still in the air. The fall time is s, just after the last row.
Answer: yes, at 4 s the height is 1.6 m. The ball lands after about 4.04 s.
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