Question

A student throws a rock horizontally off a 5.0 m tall building. The rock's initial speed is 6.0 m/s. How long will it take the rock to reach the ground? Air resistance is negligible.'

Answer 1

The rock to reach the ground in 0.569 sec.

Step-by-step explanation:

Given that,

Height = 5.0 m

Speed = 6.0 m/s

A student throws a rock horizontally off a 0.5 m tall building.

This is the distance.

So, s = 0.5 m

We need to calculate the time

Using equation of motion

`s=ut+(1)/(2)gt^2`

Where, s = distance

t = time

g = acceleration due to gravity

Put the value into the formula

`5.0=6.0* t+0.5*9.8t^2`

`4.9t^2+6.0 t-5.0 =0`

`t = 0.569\ sec`

Neglect the negative value.

Hence, The rock to reach the ground in 0.569 sec.

Answer 2

The time taken by the rock to reach the ground is 0.569 seconds.

Step-by-step explanation:

Given that,

A student throws a rock horizontally off a 5.0 m tall building, s = 5 m

The initial speed of the rock, u = 6 m/s

We need to find the time taken by the rock to reach the ground. Using second equation of motion to find it. We get :

`s=ut+(1)/(2)gt^2\\\\5=6t+(1)/(2)* 9.8t^2\\\\t=0.569\ seconds`

So, the time taken by the rock to reach the ground is 0.569 seconds. Hence, this is the required solution.