*FRICTIONAL FORCE* in the opposite direction of the way Bobby is pushing.
Friction is a force which varies but it is always opposing the direction of motion.
*APPLIED FORCE* is the force that Bobby is pushing with.
An applied force is literally the force that is applied to an object.
*WEIGHT FORCE* is also called the force of gravity. It is straight downward.
It is the weight of the object multiplied by the force of gravity. If the TV weighed 100kg, acceleration is always 9.81 m/s^2, so the weight force would be 981 N.
*NORMAL FORCE* is the force which is holding the TV above ground. The ground supplies a force upward against the TV.
Normal force is just the force that prevents the TV from falling through the ground. We don't normally realize it in our everyday life, but the floor must hold everything up because gravity is always "pushing" against it.
Answer:
Tension, T = 0.0115 N
Explanation:
Given that,
Mass of the plastic ball, m = 1.1 g
Length of the string, l = 56 cm
A charged rod brought near the ball exerts a horizontal electrical force F on it, causing the ball to swing out to a 21.0 degree angle and remain there. According to attached figure :

T is tension in the string

So, the tension in the string is 0.0115 N.
The reason the efficiency is always less than 100% is because there is always some sort of friction in the machine.
Answer: because of friction
The answer to the question above is letter D. The separation of positive and negative charges due to electric field is called an induced charge. It is a movement of electrons in a substance caused by the electric field of a nearby charged object.
If she travels for 30 minutes, and goes at 10 kilometers per hour, she travels 5 kilometers.
An hour is 60 minutes. So, to get 30, divide by 2. Just halve it all, and you will get 10 / 2 = 5.