Answer:
The friction force is 250 N
Explanation:
The desk is moving at constant velocity. This means that its acceleration is zero: a = 0. Newton's second law states that the resultant of the forces acting on the desk is equal to the product between mass (m) and acceleration (a):

In this case, we know that the acceleration is zero: a = 0, so also the resultant of the forces must be zero:
(1)
We are only interested in the forces acting along the horizontal direction, since it is the direction of motion. There are two forces acting in this direction:
- the pull, forward, F = 250 N
- the friction force, backward, 
Given (1), we have

So the force of friction must be equal to the pull:

Answer:
Here, force=20N and displacement=10m
Work=Force×Displacement=20N×10m=200Nm
Answer:
v (speed) = S / t = 4 * 400 m / (6 * 60 sec) = 4.4 m/s
The average velocity is zero because there is no net vector displacement.
<span>The expected boiling point of a substance increases with an increasing molar mass of the substance. So I would expect the lighter compounds to boil at lower temperature. Also more polar molecules tend to boil at higher temperature.
Pentane is the lightest of all three compounds, so it should boil the soonest.
Heptane is a lot heavier than Pentane, but slightly lighter than Heptanol. So it should boil next.
Heptanol is the heaviest of all of the molecules and is also quite polar compared to heptane. So it should have the highest of all the boiling points.</span>
The amount of gravitational force between both objects will be the same.
The magnitude of the Earth's gravitational force exerted on the housekeeper is calculated by applying Newton's second law of motion;
F = mg
where;
<em>m </em><em>is the mass of the housekeeper</em>
<em>g </em><em>is acceleration due to gravity</em>
According to Newton's third law of motion, action and reaction are equal and opposite.
The force exerted on the housekeeper by the Earth is equal in magnitude to the force exerted on the Earth by the housekeeper.

The two forces are equal in magnitude but opposite in direction.
Thus, the correct option is " the amount of gravitational force between both objects will be the same"
<em>The</em><em> missing part</em><em> of the </em><em>question </em><em>is below:</em>
a. the Earth exerts the largest amount of gravitational force
b. the housekeeper exerts the largest amount of gravitational force
c. the amount of gravitational force between both objects will be the same
Learn more about Newton's third law of motion here: brainly.com/question/15507