A hammer is dropped and it falls for 9 seconds 9 seconds before hitting the ground. Determine how far it falls, assuming an acceleration due to gravity of − 9.8 m/s 2 −9.8 m/s2 and no wind resistance.

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Answer:

396.9 meter

Step-by-step explanation:

If a represents the acceleration,

Then according to the question,

a = -9.8 m/s²,

[tex]\frac{dv}{dt}=-9.8[/tex]     ( acceleration = change in velocity with respect to time ),

[tex]dv = -9.8dt[/tex]

Integrating both sides,

[tex]v=-9.8t + C[/tex]

When t = 0 seconds, v = 0 m/s,

[tex]0 = -9.8(0) + C[/tex]

[tex]\implies C = 0[/tex]

[tex]\implies v=-9.8t[/tex]

[tex]\frac{dx}{dt}=-9.8t[/tex] ( velocity = change in position with respect to time ),

[tex]dx = -9.8tdt[/tex]

Integrating again,

[tex]x=-4.9t^2 + C'[/tex]

When t = 0 , x = 0 meters,

[tex]0=-4.9(0) + C'\implies C'=0[/tex]

Hence, the final equation that shows the position of the hammer after t seconds,

[tex]x=-4.9t^2[/tex]

If t = 9 seconds,

[tex]x = -4.9(9)^2 = -4.9(81) = -396.9[/tex]  ( negative sign shows the fall ),

Therefore, it will fall 396.9 meter in 9 seconds

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