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#### A rock is thrown with a speed of 50 m/s at an angle of 30 degrees with respect to the horizontal. After finding the vertical and horizontal components of the rock's velocity how long will it be in air

10 viewed last edited 2 years ago Shubhanan Kulkarni
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found horizontal and vertical components of the rock's velocity
how to find out how long it will be in the air. Basically which formula do I use to find the time and why? Mahesh Godavarti
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If you found the vertical velocity, then use that to calculate how long it will be in the air.

Do you know how to solve the problem when the rock is thrown vertically up in the air?

Let the vertical velocity be "v" then the amount of time it will take for the speed of the rock to go to zero would be v/g where g is the acceleration due to gravity (essentially \frac{\text{change in speed}}{\text{acceleration}} = \frac{0 - v}{-g} )

This is the same amount of time, it will take for the ball to come down to the ground. So, the total time it will stay up in the air will be \frac{2v}{g}.

In your particular case, the vertical velocity is given 25 m/s. So, the amount of time it will stay up in the air is 2*25/10 = 5s (assuming the acceleration due to gravity is 10 m/s2). Shubhanan Kulkarni
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Thank you very much! I think I understand the concept now!