Answer: The work is 1863 N*m
Explanation:
We can define work as:
W = F*d
Where F is the force that the mover needs to apply to the refrigerator, and d is the distance that the refrigerator is moved.
To move the refrigerator, the minimal force that the mover needs to do is exactly the friction force (In this case, the refrigerator will move with constant speed).
Then we will have:
F = 230 N
and the distance is 8.1 meters, then the work will be:
W = 230N*8.1 m = 1863 N*m
Answer:
D) the second at the doorknob
Explanation:
The torque exerted by a force is given by:

where
F is the magnitude of the force
d is the distance between the point of application of the force and the centre of rotation
is the angle between the direction of the force and d
In this problem, we have:
- Two forces of equal magnitude F
- Both forces are perpendicular to the door, so 
- The first force is exerted at the midpoint of the door, while the 2nd force is applied at the doorknob. This means that d is the larger for the 2nd force
--> therefore, the 2nd force exerts a greater torque
For any object thrown upwards where only the force of gravity is acting upon it, uses the following formula for the maximum height attained.
H= v²/2g, where g = 9.81 m/s²
There are two information of velocities are given. However, we use the 20 m/s information because this is the launch velocity. Hence, the solution is as follows:
H = (20 m/s)²/2(9.81 m/s²)
<em>H = 20.4 m</em>
Time = (distance covered) / (speed)
Time = (224 mi) / (56 mi/hr)
<em>Time = 4 hours</em>