How long does a ball take to fall from a roof to the ground 7 m below?

Answer 1

See below

If we assume that there is no air resistance and the only force acting on the ball is that of gravity, we can use the equation of motion:

#s=ut+(1/2)at^(2)#

#s#=distance travelled #u#=initial velocity (0) #t#=time to travel given distance #a#=acceleration, in this case #a=g#,the acceleration of free fall which is #9.81 ms^-2#

Hence: #7=0t + (1/2)9.81t^2#

#7=0+4.905t^2#

#7/(4.905)=t^2#

#t approx 1.195 s#

So it takes barely a second for the ball to hit the ground from that height.

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Answer 2

Axel Acevedo

The time it takes for a ball to fall from a roof to the ground 7 meters below can be calculated using the formula for free fall: ( t = \sqrt{\frac{2h}{g}} ), where ( t ) is the time, ( h ) is the height (7 meters in this case), and ( g ) is the acceleration due to gravity (approximately 9.8 m/s²). The calculation yields the time taken for the fall.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.