Question

Find time in free fall with 200m height 9.81m/per second per second acceleration with 0,3m/s initial speed​

Answer 1

6.36 s

Step-by-step explanation:

Here the free fall means that the object is subjected only to gravity force. there are no other acting forces

(Assume g = 9.8 ms⁻²)

This gravitational acceleration (g) is same through out the motion there for we can use motion equation symbols has usual meanings.

S = ut + 1/2 at²

where ,

• s - distance
• u - initial velocity
• a-acceleration
• t - time

↓S = ut + 1/2 at²

200 = 0.3 t + 1/2 × 9.8 × t²

4.9 t² + 0.3 t -200 = 0

Here you can have a quadratic equation and get a solution we can applie the formula to find the quadratic equation

Assume a quadratic equation be

ax² + bx +c =0

`solution (x) =\frac{-b+\sqrt{b^(2)-4ac } }{2a}  or \frac{-b-\sqrt{b^(2)-4ac } }{2a}`

t = -0.3 ±√0.3²-4×4.9×(-200) / (2×4.9)

t = 6.36 s or -6.42 s

but a time cannot be zero

therefore the solution should be 6.36 s