A cameraman sitting near the open door of a news helicopter accidentally drops his 140-g mobile phone out

the door at an altitude of 990 m. How fast will the phone be falling when it strikes the ground?

A. 9.8 m/s

B. 140 m/s

C. 850 m/s

D. 990 m/s

Answer:B. 140 m/s

140m/s

Explanation:

Given parameters:

Mass of mobile phone = 140g

Altitude = 990m

Unknown:

Final velocity = ?

Solution:

This is a motion problem. It is solvable by using the right motion equation. For this problem, understand that the phone is dropping under the influence of gravity.

V² = U² + 2gH

where V is the final velocity

U is the initial velocity

g is the acceleration due to gravity

H is the height of fall

Initial velocity is 0

Input the variables;

V² = 0² + 2 (9.8) (990)

V = 139.29m/s = 140m/s