Question

3. Same questions as the previous problem, but for mass m just falling 3 meters in a vacuum: (a) How long does it take mass m to fall 3 meters? (b) What is its final velocity (with direction)? (c) Explain what physics principle makes (b) be the same or different in problems (2) and (3).

Answer 1

Answer:

a) 0.78 s

b) 58.86m/s'

c) Galileo's law of free fall

Explanation:

a) $x = v_{i}t + \frac{1}{2}at^{2} \\3 = 0*t+\frac{1}{2} *9.81*t^{2}\\t=\sqrt{\frac{6}{9.81} }$

b)At the bottom:

kinetic energy = potential energy

$\frac{1}{2}mv^{2} = mgh\\ v^{2} =2*9.81*3=58.86m/s$ downwards

c) Galileo's law of free fall says regardless of the masses, bodies in a vacuum will fall, on the earth, at the same acceleration