Question

Твердое тело плавиться при постоянной температуре, При этом внутренняя энергия увеличитсяуменьшитсяне изменитсяпревращается в механическую энергиюдругое Скорость движения автобуса задана уравнением V=20 - 2t (все величины в единицах СИ). Чему равен импульс автобуса через 5с после начала движения? Масса автобуса 2,7 тонны. * может быть несколько правильных ответов 27 кг*м/с27000кг*м/с2,7*10^4 кг*м/с27*10^3 кг*м/снет правильного ответа В инерциальной системе отсчета сила F сообщает телу массой m ускорение а. Как изменится модуль ускорения тела, если и массу тела, и модуль действующей на него силы уменьшить в 3 раза? *увеличится в 9 разуменьшится в 9 разуменьшится в 81 разне изменится

Answer 1

- внутренняя энергия увеличивается

-

V=20-2*5=10м/с      р=mV= 2700*10= 27 000 кгм/с = 2,7*10^4 = 27*10^3

 

-     F=ma        F/3= m/3 * a      не изменится

Answer 2

Melting of a Solid at Constant Temperature

When a solid melts at a constant temperature, its internal energy remains constant. The energy supplied to the solid is used to break the intermolecular forces holding the solid together, rather than increasing the internal energy of the solid itself. Therefore, the internal energy of the solid does not change during the melting process [[1]].

Impulse of the Bus

To find the impulse of the bus, we need to calculate the change in momentum of the bus. The impulse-momentum theorem states that the impulse experienced by an object is equal to the change in its momentum.

The momentum of an object is given by the product of its mass and velocity. In this case, the mass of the bus is given as 2.7 tonnes, which is equivalent to 2.7 * 10^3 kg. The velocity of the bus is given by the equation V = 20 - 2t, where t is the time in seconds.

After 5 seconds, the velocity of the bus can be calculated as follows: V = 20 - 2 * 5 = 20 - 10 = 10 m/s

The momentum of the bus is given by: Momentum = mass * velocity =#### Melting of a Solid at Constant Temperature

When a solid melts at a constant temperature, its internal energy does not change. The energy added to the solid is used to overcome the forces holding the solid together, rather than increasing the internal energy. This process is known as a phase change, and the energy added is called the latent heat of fusion. Therefore, the internal energy of the solid remains constant during the melting process .

Impulse of the Bus

The impulse of the bus can be calculated using the formula:

Impulse = Force × Time = Change in Momentum

The velocity of the bus is given by the equation: V = 20 - 2t

To find the impulse after 5 seconds, we need to calculate the change in momentum. The momentum of an object is given by the product of its mass and velocity: p = mv.

Given that the mass of the bus is 2.7 tonnes, which is equal to 2700 kg, we can calculate the velocity of the bus after 5 seconds using the given equation.

Substitute t = 5 into the equation V = 20 - 2t: V = 20 - 2(5) = 20 - 10 = 10 m/s

Now, we can calculate the momentum of the bus: p = mv = 2700 kg × 10 m/s = 27000 kg*m/s

Therefore, the impulse of the bus after 5 seconds is 27000 kg*m/s.

Change in Acceleration of a Body

If the mass of a body and the magnitude of the force acting on it are both reduced by a factor of 3, the acceleration of the body will increase by a factor of 9. This can be understood using Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. When both the force and the mass are reduced by a factor of 3, the acceleration increases by a factor of 3/1, resulting in an increase by a factor of 9.

Therefore, if both the mass and the magnitude of the force acting on the body are reduced by a factor of 3, the acceleration of the body will increase by a factor of 9.