Answer:
O B. when the angle between the force and displacement is 90°
Explanation:
<h3>work defined as

. </h3><h3>work can only be done if object moves(displacement) in the direction of force. now a quick one. if you since the varrious angles into the cosine, you would see that Cos 90 will give zero which implies that no work is done. Again, angle means it is perpendicular and so it is not in the direction of force.</h3>
To give solution to the exercise we must use the concepts of Torque, Vector magnitude and vector direction of the forces.
For the given problem we have to


In this way the torque acting on the particle as a function of distance and time is,

The net torque acting on the particle is



PART B) The direction of the torque is given by,




Therefore the torque direction is 48.04° below the x axis.
Answer:
25N
Explanation:
Given parameters:
Power of the motor = 125W
Average speed = 5m/s
Unknown:
Force supplied to the motor = ?
Solution:
Work done is the force applied to move a body through a particular distance;
Work done = Force x distance
Also,
Work done = Power x time
So;
Force x distance = Power x time
since force is the unknown;
Force =
Speed =
Force =
Now solve;
Force =
= 25N
Answer: Electromagnetic waves are generated by moving electrons. An electron generates an electric field which we can visualize as lines radiating from the electron Figure 10a. If the electron moves, say it vibrates back and forth, then this motion will be transferred to the field lines and they will become wavy Figure 10b.