# Stone launched vertically upward from top of cliff

1) Luigi launches a stone vertically upward from the top of a cliff. The height of the stone above the base of the cliff is appoximated by the model h=65+10t-5t^2

where t is time in second and h is height in metres

a) how high is the stone above the base of the cliff after 3 seconds?

h = 65 + 10t - 5t^2

h = 65 +10(3) - 5(3)^2

h = 65 +30 - 45

h = 50 m

b) How long does it take for the stone to reach 50m above the base of the cliff?

h = 65 + 10t - 5t^2

h = 65 + 10t - 5t^2

-65 + 50 = 10t - 5t^2

-15 = 10t - 5t^2

can someone help me from here?

c) How long does it take for the stone to hit the ground at the base of the cliff?

I do not know about how to go about completing this one,

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Can anyone help?

Hi, I have started work on these questions but I do not know if I am doing them right, or how to go about the others.

1) Luigi launches a stone vertically upward from the top of a cliff. The height of the stone above the bsae of ...

#### Solution Summary

The solution discusses how high the stone above the base of the cliff is.