Answer:
-4.72005 m/s
0 m/s
Explanation:
Displacement = 5220 km
Time = 12.8 days
The average velocity is given by
The average for the return flight is -4.72005 m/s
When the total displacement is divided by the total time of a journey then we get the average velocity.
Displacement is the minimum distance between the initial and final points of the journey.
Here, the displacement of the whole episode is 0 as the initial and final point is zero.
Hence, the average velocity for the whole episode is 0 m/s
It has to be used because you can not visually see them
The forces acting on the elevator are:
Gravity force
Tension force
Air resistance
Explanation:
Let's go through each of the forces listed and see which ones are acting on the elevator.
- Normal force: NO. The normal force is a force exerted by a surface whenever there is another object "pushing" on it. For instance, when a box is at rest on a table, the box is "pushing" on the table (due to its weight), and the table "pushes back" on the box, upward, in order to balance its weight: this is the normal force. In this case, the elevator is lifted, so it is not pushing on anything, therefore there is no normal force.
- Gravity force: YES. The force of gravity acts on every object located in the gravitational field of the Earth; it pulls downward, and its magnitude is
, where m is the mass of the object and g is the acceleration of gravity. - Applied force: NO. Here there is no applied force, since there is nobody "pushing" or "pulling" the elevator.
- Friction force: NO. As we are considering the forces on the elevator, and the elevator is not sliding against any surfaces, there is no force of friction. (The force of friction acts whenever there are two surfaces sliding against each other, which is not the case here)
- Tension force: YES. The tension force is the force exerted by a rope or a string when pulling an object. In this case, there are four ropes pulling the elevator, therefore there are 4 forces of tension acting on the elevator, upward.
- Air resistance: YES. As the elevator is moving through the air, the interaction between the molecules of air with the surface of the elevator produces a force (called air resistance) that "resists" the motion of the elevator, therefore pushing downward. However, the magnitude of this force is negligible in this case.
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The force exerted on the box is 56 N
Explanation:
The work done by a force on an object is given by
where
F is the magnitude of the force
d is the displacement of the object
is the angle between the direction of the force and of the displacement
For the box in this problem, we have:
W = 2240 J is the work done
d = 40 m is the displacement of the box
Assuming that the force is parallel to the displacement, 
Solving the equation for F, we find the force exerted on the box:
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Answer:
Given:
Mass (m) = 3.0 kg
Uniform speed (v) = 20 m/s
Length of string (r) = 40 cm = 0.4 m
To Find:
Tension in the string (T)
Explanation:
Tension (T) is the string will be equal to centripetal force (
).
Substituting value of m, v & r in the equation:
Tension in the string (T) = 3 kN
