# When an object is dropped from a height of 620 m, what is the time taken for it to reach the ground. The distance traveled by an object (d) moving with an initial speed (u) and which is accelerating at a rate a is t where d = u*t + (1/2)*a*t^2.

In the problem, the object has been dropped from a height of 620 m, the initial speed of the object in...

The distance traveled by an object (d) moving with an initial speed (u) and which is accelerating at a rate a is t where d = u*t + (1/2)*a*t^2.

In the problem, the object has been dropped from a height of 620 m, the initial speed of the object in this case is 0 m/s. The gravitational force of attraction accelerates the object downwards at 9.8 m/s^2. The distance traveled by the object before it strikes the ground is 620 m.

Substituting d = 620, a = 9.8, u = 0 gives the equation:

`620 = 0*t + (1/2)*9.8*t^2`

=> `620 = (1/2)*9.8*t^2`

=> `t^2 = 6200/49`

=> `t ~~ 11.24`

When dropped from a height of 620 m, the object strikes the ground after 11.24 seconds.

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