Answer:

Explanation:
Force on a current carrying rod due to magnetic field is given as

here we know that
current in the rod


now magnetic force is balanced by the weight of the rod
so we will have



Explanation:
Below is an attachment containing the solution.
Answer:
The magnitude of buoyancy force is equal to that of ball's weight.
Explanation:
Ball 1 is floating on water. Weight of ball 1 is Fg=m1g is acting vertically downward
Force of buoyancy FB = ρVdisg is acting vertically upward.
Net force acting on the ball is zero, FB=Fg
Answer
The magnitude of buoyancy force is equal to that of ball's weight.
Answer:
The mass of Laura and the sled combined is 887.5 kg
Explanation:
The total force due to weight of Laura and friction on the sled can be calculated as follows;

= (400 + 310) N
= 710 N
From Newton's second law of motion, "the rate of change of momentum is directly proportional to the applied force.

where;
is mass of Laura and
is mass of sled
Mass of Laura and the sled combined is calculated as follows;

given
V = Δv = 4-0 = 4m/s
t = 5 s

Therefore, the mass of Laura and the sled combined is 887.5 kg
I think it’s c. if not i’m sorry!!