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Question
A cricket ball is droped from a height of 20 metres.
calculate the speed of the ball when it hits the ground.
IN THIS QUESTION CAN WE TAKE FINAL VELOCITY,DISPLCEMENT S AND ACCELERATION DUE TO GRAVITY AS NEGATIVE?
calculate the speed of the ball when it hits the ground.
IN THIS QUESTION CAN WE TAKE FINAL VELOCITY,DISPLCEMENT S AND ACCELERATION DUE TO GRAVITY AS NEGATIVE?
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Solution
velocity(u)=0m/sec
final velocity(v)=x m/sec
distance(s)=20m
acceleration due to gravity(g)=9.8m/s²
'.'v²=u²+2as
.'.x²=0+2X9.8X20(where 'X' is sign of product)
⇒x²=392
⇒x=√392
⇒x=17.79898987322333 m/s
yes we can take acceleration due to gravity and velocity as negative
but displacement will only be negative if the refrance point /origin taken is the initial point.
final velocity(v)=x m/sec
distance(s)=20m
acceleration due to gravity(g)=9.8m/s²
'.'v²=u²+2as
.'.x²=0+2X9.8X20(where 'X' is sign of product)
⇒x²=392
⇒x=√392
⇒x=17.79898987322333 m/s
yes we can take acceleration due to gravity and velocity as negative
but displacement will only be negative if the refrance point /origin taken is the initial point.
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