If a 4.5 kg object is dropped from a height of 6.0 m, what will be its velocity when it is halfway toward the ground? (Use g = 9.80 m/s2, and ignore air resistance.) 7.7 m/s 11 m/s 16 m/s 29 m/s

Question

Kadyn Taylor

Physics

19 October, 06:05

If a 4.5 kg object is dropped from a height of 6.0 m, what will be its velocity when it is halfway toward the ground? (Use g = 9.80 m/s2, and ignore air resistance.) 7.7 m/s 11 m/s 16 m/s 29 m/s

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Darnell Hardin · Answer 1

When an object falls or is dropped from rest it's initial velocity is zero.

Using the equations for a motion in straight line. I can find the time it takes to reach 3.0 m down (half way).

x = vt - 4.9t²

-3 = 0 - 4.9t²

-3/-4.9 = t²

0.6122 = t²

0.7825 sec = t

v = v - gt

v = 0 - 9.8 (0.7825)

v = - 7.67 m/s

the negative denotes downward direction.

You could also solve the problem using potential and kinetic energy.

Since it starts with maximum PE and gets converted to KE when it hits the ground. mgh = mv²/2

mass cancels, use 3 meters for the halfway distance

-9.8 (-3) = v²/2

29.4 * 2 = v²

√ (58.8) = 7.67 m/s downwards