Answer:
B = 0.8 T
Explanation:
It is given that,
Radius of circular loop, r = 0.75 m
Current in the loop, I = 3 A
The loop may be rotated about an axis that passes through the center and lies in the plane of the loop.
When the orientation of the normal to the loop with respect to the direction of the magnetic field is 25°, the torque on the coil is 1.8 Nm.
We need to find the magnitude of the uniform magnetic field exerting this torque on the loop. Torque acting on the loop is given by :

B is magnetic field

So, the magnitude of the uniform magnetic field exerting this torque on the loop is 0.8 T.
Answer:
C. 
Explanation:
Let initial charges on both spheres be,

When the sphere C is touched by A, the final charges on both will be,
#Now, when C is touched by B, the final charges on both of them will be:

Now the force between A and B is calculated as:

Hence the electrostatic force becomes 3F/8
Answer:
1.67 m/s
Explanation:
Momentum is conserved.
Initial momentum = final momentum
(30 kg) (10 m/s) + (35 kg) (-10 m/s) = (30 kg) v + (35 kg) (0 m/s)
300 - 350 = 30v
v = -5/3 m/s
Linus will move at 1.67 m/s in the direction opposite that he started.
Answer:
B, the car travels around a circular track at 30 m.
Explanation: