Question

Мяч массой 100 грамм бросили вертикально вниз от поверхности земли. Поднявшись на высоту 2 м, мяч начал падать вниз, и его поймали на высоте 0,5 м от земли. Чему была равна кинетич. энергия мяча на этой высоте? Сопротивлением воздуха можно пренебречь.

Answer 1

Решение:
gt²=1.5м
9.8t²=1.5
t=0.39

V=0.39·g=3.82
E=mV²=0.1·3.82²=1.46 Дж

Answer 2

Calculation of the Kinetic Energy of the Ball

To calculate the kinetic energy of the ball at a height of 0.5 m from the ground, we can use the formula for gravitational potential energy:

Potential Energy (PE) = mass (m) × acceleration due to gravity (g) × height (h)

Since the ball is dropped vertically downward, its initial velocity is zero. Therefore, the initial kinetic energy is also zero.

At a height of 2 m, the ball starts falling downward. When it reaches a height of 0.5 m, its potential energy is converted into kinetic energy.

To find the kinetic energy at a height of 0.5 m, we need to subtract the potential energy at that height from the initial potential energy at a height of 2 m.

Let's calculate the potential energy at a height of 2 m first:

Potential Energy at 2 m (PE2) = mass (m) × acceleration due to gravity (g) × height (2 m)

Now, let's calculate the potential energy at a height of 0.5 m:

Potential Energy at 0.5 m (PE0.5) = mass (m) × acceleration due to gravity (g) × height (0.5 m)

Finally, we can calculate the kinetic energy at a height of 0.5 m by subtracting the potential energy at 0.5 m from the potential energy at 2 m:

Kinetic Energy at 0.5 m (KE0.5) = PE2 - PE0.5

Now, let's plug in the values and calculate the kinetic energy.

Given: - Mass of the ball (m) = 100 grams = 0.1 kg - Height at which the ball starts falling (h2) = 2 m - Height at which the ball is caught (h0.5) = 0.5 m - Acceleration due to gravity (g) = 9.8 m/s^2

Calculations: - PE2 = 0.1 kg × 9.8 m/s^2 × 2 m = 1.96 J - PE0.5 = 0.1 kg × 9.8 m/s^2 × 0.5 m = 0.49 J - KE0.5 = PE2 - PE0.5 = 1.96 J - 0.49 J = 1.47 J

Therefore, the kinetic energy of the ball at a height of 0.5 m from the ground is 1.47 Joules.