Question

100 POINTS plz help Chuck drops a rock from a height of 70 m. How long will it take the rock to hit the ground?

Use the formula h(t)=−4.9t2+v0t+h0, where v0 is the initial velocity and h0 is the initial height.


Round to the nearest tenth of a second. Enter your numeric answer.

Answer 1

3.8 seconds

Explanation:

h(t) = −4.9t² + v0t + h0,

0 = -4.9t² + 70

4.9t² = 70

t² = 100/7

t = 3.77964473

Answer 2

3.8

Explanation:

We are going to plug in the values of the equation, so h(t)=-4.9^2+v0t+h0 will

now be h(t)=-4.9^2+0+70

Now we will find the a b and c of the equation, a=-4.9 b=0 c=70

Now we must find the discriminant of the equation, which the equation for that is D=b^2+(-4)(a)(c)

So D=1,372

Now we use the quadratic formula (see picture below for finished product)