Question

An object is falling from a height of 7.5 meters. At what height will its velocity be 7 meters/second?

Answer 1

5.0m

Step-by-step explanation:

Answer 2

5.0 m

Step-by-step explanation:

The velocity of the object at time t is given by

`v=at`

where a=9.8 m/s^2 is the acceleration of gravity and t is the time. If we substitute v=7 m/s, we can find the time t at which the velocity became 7 m/s:

`t=(v)/(a)=(7 m/s)/(9.8 m/s^2)=0.71 s`

The height of the object at time t, h(t), is given by the equation

`h(t)=h_0 -(1)/(2)at^2`

where
`h_0 = 7.5 m` is the initial height. By substituting t=0.71 s inside the equation, we find the height h(t) at which the velocity is 7 m/s:

`h(0.71 s)=7.5 m- (1)/(2)(9.8 m/s^2)(0.71 s)^2=5.0 m`