Answer:
900 J
Explanation:
= Change in entropy = -300 J (Decrease)
= Work done = 600 J
= Heat transferred
Change in internal energy is given by

The heat transferred to or from the system as heat is -900 J.
900 J is transferred. As heat is transferred from the system the sign is negative.
<span>Yes, it's possible to hoist the child up.
Let's first determine the maximum amount of pull that the woman can exert. That will be the simple product of her weight and the coefficient of static friction with her shoes and the ground. So
0.8 * 190 = 152.
So far, so good, since 152 is greater than the boy's 80 lbs. But the cable rubs at the cliff edge and that means that the lady has to pull harder. Let's see how much harder.
There will be 80 lbs of tension on the cable, pressing against the cliff edge. So let's multiply by the coefficient of friction to get how much that is
0.2 * 80 = 16
So friction will take 16 lbs of effort to overcome. So the lady needs to pull with 80 + 16 = 96 lbs of force to move the boy. And since we've determined earlier that she can pull with up to 152 lbs of force, she can easily hoist the child up.</span>
Answer:
Closed system, because the speed of the car is as expected in the case where an object has uniform acceleration for a time t
Explanation:
Here in the question it is mentioned that a toy car has an initial acceleration of 2m/s² across a horizontal surface so we can say that it is acted upon by an external force
Assuming that the acceleration is constant and the reason for this assumption is there at the last
The major difference between an open system and closed system is in case of open system there will be transfer of matter and in case of closed system there will be no change in matter of the system
If acceleration is constant in case of closed system we can expect the speed of the car after a time t by using the formula
s = u×t + 0·5×a×t²
where s is the distance travelled
t is the time taken to travel that distance
u is the initial velocity
a is the acceleration of that system
But in case of open system as there will be a change of mass there will be a change in velocity of the system so in this case we cannot expect the speed of the car after a time t
And if the acceleration is not constant then we cannot say that the toy car is an open system or closed system, that is why we are assuming that the acceleration of the toy car is constant
Answer:
A fast feather
Explanation:
The faster any item is, the more momentum it has