A heat pump is a device used to heat something, in this case water. Heat pump takes heat from colder object and transfers it to warmer object. This is opposite to <span>direction of spontaneous heat transfer which from warmer to colder object.
In this problem a room got colder while water got warmer. This is due to work done by heat pump. This is what is described in correct answer c).
a) is not correct because it shows </span>direction of spontaneous heat transfer. It also says that <span>Aleksei’s family purchased a new water heater and in description givne in a) it would mean that water got colder.
b) is not correct because if the </span><span>burning fuel increased the thermal energy in the air it would mean that this room got warmer than rest of house.
d) is not correct because burning fuel does not absorb </span><span>thermal energy. It releases it.</span>
Less than or equal to the magnitude of the vector
Answer:

Explanation:
Work is equal to the product of force and distance.

The force is 8 Newtons and the distance is 15 meters.

Substitute the values into the formula.

Multiply.

- 1 Newton meter is equal to 1 Joule
- Our answer of 120 N*m equals 120 J

The work done is <u>120 Joules</u>
C. is correct : ) it is applied when you push and that causes the desk to move
Answer
(C).
When there is an angle between the two directions, the cosine of the angle must be considered.
Step by step Solution
The work done by a force is defined as the product of the force and the distance traveled in the direction of motion.
The first answer "Only the component of the force perpendicular to the motion is used to calculate the work" is wrong because, the force perpendicular to motion does no work.
The second choice "If the force acts in the same direction as the motion, then no work is done" is wrong because the work in the direction of the force is
.
Fourth answer "A force at a right angle to the motion requires the use of the sine of the angle" is wrong because the
meaning that there is no work done in the direction perpendicular to the motion.
The third answer" When there is an angle between the two directions, the cosine of the angle must be considered." is correct because the work is calculated using the force in the direction of the motion. The magnitude of this force is 