Question

Камень массой 200 г брошен с горизонтальной поверхности под углом к горизонту упал на нее на расстоянии 40 м через 4 с. Чему равна работа затраченная на этот бросок? Cопротивление не учитывать. Помогите пожалуйста

Answer 1

M=200 г=0,2 кг.1) Найдем силу тяжести по первому закону Ньютона:F=m*g=0,2*10=2 Н2) Работа: A=F*s=2*40=80 Дж.3) Мощность: N=A/t=80/4=20 Вт.Ответ: А=80 Дж; N=20 Вт.

Answer 2

Calculation of Work Done

To calculate the work done on the stone during the throw, we need to consider the change in kinetic energy of the stone. The work done is equal to the change in kinetic energy.

The initial kinetic energy of the stone can be calculated using the formula:

K1 = (1/2) * m * v1^2

where: - K1 is the initial kinetic energy - m is the mass of the stone (200 g or 0.2 kg) - v1 is the initial velocity of the stone

The final kinetic energy of the stone can be calculated using the formula:

K2 = (1/2) * m * v2^2

where: - K2 is the final kinetic energy - m is the mass of the stone (200 g or 0.2 kg) - v2 is the final velocity of the stone

Since the stone falls vertically downward, the vertical component of the velocity remains constant. Therefore, the final velocity in the vertical direction is equal to the initial velocity in the vertical direction.

The horizontal component of the velocity remains constant as there is no horizontal force acting on the stone. Therefore, the final velocity in the horizontal direction is equal to the initial velocity in the horizontal direction.

The work done on the stone can be calculated as the difference between the initial and final kinetic energies:

Work = K2 - K1

Calculation of Initial Velocity

To calculate the initial velocity of the stone, we can use the equation of motion:

s = ut + (1/2) * a * t^2

where: - s is the distance traveled by the stone (40 m) - u is the initial velocity of the stone - a is the acceleration of the stone (in this case, the acceleration due to gravity, which is approximately 9.8 m/s^2) - t is the time taken for the stone to travel the distance (4 s)

Rearranging the equation, we get:

u = (s - (1/2) * a * t^2) / t

Substituting the given values, we can calculate the initial velocity.

Calculation of Work Done

Now, let's calculate the work done on the stone.

Using the formulas mentioned earlier, we can calculate the initial and final kinetic energies of the stone.

The initial kinetic energy (K1) is given by:

K1 = (1/2) * m * v1^2

The final kinetic energy (K2) is given by:

K2 = (1/2) * m * v2^2

Since the stone falls vertically downward, the vertical component of the velocity remains constant. Therefore, the final velocity in the vertical direction is equal to the initial velocity in the vertical direction.

The horizontal component of the velocity remains constant as there is no horizontal force acting on the stone. Therefore, the final velocity in the horizontal direction is equal to the initial velocity in the horizontal direction.

The work done on the stone can be calculated as the difference between the initial and final kinetic energies:

Work = K2 - K1

Let's calculate the values step by step.

Calculation Steps:

1. Calculate the initial velocity (u) using the equation of motion:

u = (s - (1/2) * a * t^2) / t

Substituting the given values: - s = 40 m - a = 9.8 m/s^2 - t = 4 s

u = (40 - (1/2) * 9.8 * 4^2) / 4

2. Calculate the initial kinetic energy (K1) using the formula:

K1 = (1/2) * m * v1^2

Substituting the given values: - m = 0.2 kg (mass of the stone) - v1 = u (initial velocity)

K1 = (1/2) * 0.2 * u^2

3. Calculate the final kinetic energy (K2) using the formula:

K2 = (1/2) * m * v2^2

Substituting the given values: - m = 0.2 kg (mass of the stone) - v2 = u (final velocity)

K2 = (1/2) * 0.2 * u^2

4. Calculate the work done (Work) using the formula:

Work = K2 - K1

Substituting the values of K2 and K1:

Work = [(1/2) * 0.2 * u^2] - [(1/2) * 0.2 * u^2]

The work done is equal to zero since the initial and final kinetic energies are the same.

Therefore, the work done on the stone during this throw is zero.

Please note that this calculation does not take into account any resistance or air friction.