Homework Help

A small object, of mass 0·02kg at the top of a building 160 m high, is dropped from...

user profile pic

saj-94 | Salutatorian

Posted July 28, 2013 at 11:24 AM via web

dislike 1 like

A small object, of mass 0·02kg at the top of a building 160 m high, is dropped from rest.

(a) Ignoring air resistance, calculate

  1. the speed of the object as it hits the ground and the time taken for the object to reach the ground.

Tagged with science

1 Answer | Add Yours

user profile pic

jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted July 28, 2013 at 11:33 AM (Answer #1)

dislike 1 like

We can use the equations of motion here.

`darrV^2 = U^2+2aS`

`V = ?`

`U = 0` as it is dropped.

`a = 9.81m/s^2`

`S = 160m`

`V^2 = 0+2xx9.81xx160`

`V^2 = 3139.2`

`V = 56.03m/s`

Using `darrV = U+at`

`t = (V-U)/a`

`t = (56.03-0)/9.81`

`t = 5.71s`

So when the ball hit the ground the velocity will be 56.03 and 5.71 seconds will be the time taken.

Sources:

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes