Question

Шарик массой 150 грамм падает с высоты 20 м из состояния покоя. Какова его кинетическая энергия в момент падения на землю, если сопротивление воздуха пренебрежимо мало?

Answer 1

По закону сохр. мех энергии кинет. энергия при падении равна потенциальной в состоянии покоя на высоте 20 м.

Wкин = mgh

Wкин = 0,15 *10*20 = 30 Дж

Ответ: 30 Дж.

Answer 2

Calculation of Kinetic Energy

To calculate the kinetic energy of an object, we can use the formula:

Kinetic Energy (KE) = 1/2 * mass * velocity^2

In this case, the object is a ball with a mass of 150 grams (0.15 kg) and it falls from a height of 20 meters. Since the resistance of the air is negligible, we can assume that the ball will reach its maximum velocity just before hitting the ground.

To find the velocity, we can use the equation of motion:

v^2 = u^2 + 2 * g * h

Where: - v is the final velocity (which is the velocity just before hitting the ground) - u is the initial velocity (which is 0 m/s since the ball starts from rest) - g is the acceleration due to gravity (approximately 9.8 m/s^2) - h is the height (20 meters)

Using this equation, we can calculate the final velocity:

v^2 = 0^2 + 2 * 9.8 * 20

v^2 = 0 + 392

v^2 = 392

v ≈ 19.8 m/s

Now that we have the velocity, we can calculate the kinetic energy:

KE = 1/2 * mass * velocity^2

KE = 1/2 * 0.15 * (19.8)^2

KE ≈ 0.15 * 19.8^2

KE ≈ 0.15 * 392.04

KE ≈ 58.806 Joules

Therefore, the kinetic energy of the ball at the moment it hits the ground is approximately 58.806 Joules.