Question

A 5kg pumpkin is dropped from the roof of the school. If the school is 10 m tall, what is the final velocity of the pumpkin when it hits the ground? (if something is just dropped, what is its initial velocity? Acceleration due to gravity = 9.81 m/s2

Answer 1

A 5kg pumpkin is dropped from the roof of the school. If the school is 10 m tall, what is the final velocity of the pumpkin when it hits the ground? (if something is just dropped, what is its initial velocity? Acceleration due to gravity = 9.81 m/s²

The law of conservation of energy:

$$T + U = \text{const}$$

$T = \frac{mv^2}{2}$ - kinetic energy, m - mass of the body, v - speed

$U = mgh$ - potential energy, g - gravitational acceleration, h - high

If pumpkin is just dropped, $v_0 = 0$

$$0 + mgh = m v^2 / 2 + 0$$ $$v = \sqrt{2gh} = \sqrt{2 * 9.81 \frac{m}{s^2} \cdot 10 \, m} = 14.0 \, \frac{\mathrm{m}}{\mathrm{s}}$$

Answer: $14.0 \, \frac{\mathrm{m}}{\mathrm{s}}$