Question

An object thrown vertically upward reaches a height of 500m. What was its initial velocity? How Will the object take to come back to the earth (Assume that g=10m/s^2)
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Answer 1

Hi,

Here is your answer

Given:

Height=Distance(s)=500m

Final velocity(v)=0m/s

Acceleration due to gravity(g)=10m/s²

To Find:

Initial velocity(u)

Time taken(t)

Solution:

We know the equation

v²-u²=2as

Here a=g

Substituting the given datas in the equation we get,

0²-u²=2×-10×500(g is taken as negative since the direction is opposite to that of motion of the object)

-u²= -10000

u=100m/s

We also know the equation

v=u+at

Substitute the datas in the equation

We get,

0=100+-10×t

t=10s

Since the object has to travel up and come back down

Total time taken=t+t=20s

Notes:

The three equations of motion are:

• v=u+at
• s=ut+1/2at²
• v²-u²=2as

Hope this helps you.