Answer:
Magnetic force, F = 0.262 N
Explanation:
It is given that,
Magnetic field of an electromagnet, B = 0.52 T
Length of the wire, 
Current in the straight wire, i = 10.5 A
Let F is the magnitude of force is exerted on the wire. The magnetic force acting on an object of length l is given by :


F = 0.262 N
So, the magnitude of force is exerted on the wire is 0.262 N.
Answer:
Diana's speed relative to ground is <u>16 km/h</u> in the direction of motion of train.
Explanation:
Given:
Velocity of train in forward direction is, 
Here, 
Velocity of Diana relative to train in the backward direction is, 
Negative sign implies backward motion or motion opposite to the direction of train's motion. Here, Diana is walking from front of train to back. So, Diana is moving in the opposite direction.
Now, we know that, for two bodies 'A' and 'B', velocity of 'A' relative to ground is given as:

Therefore, velocity of Diana relative to ground is given as:



So, Diana's speed relative to ground is 16 km/h in the direction of motion of train.
Answer:
C
Explanation:
The mechanical advantage is always less than 1 because the force needed to move an object is always greater than the weight of the object.
D. It decreases to one half.
Answer:
the force that attracts a body toward the center of the earth, or toward any other physical body having mass.