A) The resultant force is 30.4 N at 
B) The resultant force is 18.7 N at 
Explanation:
A)
In order to find the resultant of the two forces, we must resolve each force along the x- and y- direction, and then add the components along each direction to find the components of the resultant.
The two forces are:
at
above x-axis
at
above y-axis
Resolving each force:


So, the components of the resultant are:

And the magnitude of the resultant is:

And the direction is:

B)
In this case, the 15 N is applied in the opposite direction to the 20 N force. Therefore we need to re-calculate its components, keeping in mind that the angle of the 15 N force this time is

So we have:

So, the components of the resultant this time are:

And the magnitude is:

And the direction is:

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The amount of heat required is B) 150 J
Explanation:
The amount of heat energy required to increase the temperature of a substance is given by the equation:

where:
m is the mass of the substance
C is the specific heat capacity of the substance
is the change in temperature of the substance
For the sample of copper in this problem, we have:
m = 25 g (mass)
C = 0.39 J/gºC (specific heat capacity of copper)
(change in temperature)
Substituting, we find:

So, the closest answer is B) 150 J.
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Answer:
Explanation:
The moment of inertia is the integral of the product of the squared distance by the mass differential. Is the mass equivalent in the rotational motion
a) True. When the moment of inertia is increased, more force is needed to reach acceleration, so it is more difficult to change the angular velocity that depends proportionally on the acceleration
b) True. The moment of inertia is part of the kinetic energy, which is composed of a linear and an angular part. Therefore, when applying the energy conservation theorem, the potential energy is transformed into kinetic energy, the rotational part increases with the moment of inertia, so there is less energy left for the linear part and consequently it falls slower
c) True. The moment of inertial proportional to the angular acceleration, when the acceleration decreases as well. Therefore, a smaller force can achieve the value of acceleration and the change in angular velocity. Consequently, less force is needed is easier
Average speed =
(total distance covered)
divided by
(total time spent covering the distance)