Advanced MathEasy–MediumTime for a dropped stone to land
Advanced Math practice question
A stone is dropped from a cliff. Its height h, in metres, above the ground t seconds later is given by h(t) = 80 − 5t². After how many seconds does the stone hit the ground?
Answer: 4
Set h = 0: 5t² = 80, so t² = 16 and t = 4.
Common wrong answers
- If you answered 2
- 2 gives h = 60.
- If you answered 8
- 8 divides 80 by 10.
- If you answered 16
- 16 is t², not t.
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