Answer:
zero
Explanation:
For the box remaining at rest, the total acceleration on the box must be zero. Since force F = m*a, the force F must also be zero.
Answer:
66.7%
Explanation:
There are 6 pulleys, so the mechanical advantage is 6.
The theoretical force needed to overcome 1200 N is therefore:
1200 N / 6 = 200 N
The actual force is 300 N. So the efficiency is:
200 N / 300 N × 100% = 66.7%
Average speed =
(total distance covered)
divided by
(total time spent covering the distance)
If we have a moving electric charge with the velocity v, then the magnetic field will produce a force F=q*v*B*sinθ where q is the charge, v is the velocity, B is the strength of the magnetic field and θ is the angle of the velocity and the magnetic field. The force will only change the direction of the charge, and it's magnitude will be the greatest when the velocity and the magnetic field are perpendicular to each other and no force will act on the charge if θ=0. If the velocity of the charge is 0, again there is no force on the charge. We can get the direction of the force with the right hand rule.
