Answer
Hi,
The forces are; weight (gravity), Normal/centripetal force and friction. Force due to gravity is constant where as friction and centripetal are not.
Explanation
Weight is constant, given by the force of gravity on the object. The centripetal force is a function of the angles occurring between the velocity vector and the weight vector that is at right angle with the perpendicular line drawn from the surface. Friction is a function of the centripetal force thus it also varies.
Hope this helps!
Explanation:
Current output at the battery will be current of entire circuit, while the current through each bulb in the parallel circuit is the total current circuit.
So, current output through power supply is i and current through each component be
considering only three component.
Then in a parallel circuit

Answer:

Explanation:
F = Force on the sled = 63 N
m = Mass of sled = 28.7 kg
= Coefficient of kinetic friction = 0.169
g = Acceleration due to gravity = 
The force balance of the system is given by

The acceleration of the sled is
.