Мотор экскаватора имеет мощность 14,7 кВт. За час экскаватор поднял 300 т земли на высоту 1,8 м. Каков коэффициент полезного дей
1 answer:
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As we know from the Newton's II law we can say
here if force is unbalanced then it is for sure that net force on the system is non zero
so here the object must have some acceleration here
so here we can say that object must have change in velocity due to unbalanced force present on it
now the correct option in this case must satisfy the change in velocity condition.
SO correct answers will be
<em>Decelerate. </em>
<em>Stop moving. </em>
<em>Start moving. </em>
<em> Accelerate. </em>
Answer:
They collide, couple together, and roll away in the direction that <u>the 2m/s car was rolling in.</u>
Explanation:
We should start off with stating that the conservation of momentum is used here.
Momentum = mass * speed
Since, mass of both freight cars is the same, the speed determines which has more momentum.
Thus, the momentum of the 2 m/s freight car is twice that of the 1 m/s freight car.
The final speed is calculated as below:
mass * (velocity of first freight car) + mass * (velocity of second freight car) = (mass of both freight cars) * final velocity
(m * V1) + (m * V2) = (2m * V)
Let's substitute the velocities 1m/s for the first car, and - 2m/s for the second. (since the second is opposite in direction)
We get:
solving this we get:
V = - 0.5 m/s
Thus we can see that both cars will roll away in the direction that the 2 m/s car was going in. (because of the negative sign in the answer)