Answer:
B. positive; negative.
Explanation:
From the viewpoint of Principle of Energy Conservation and Work-Energy Theorem, we notice that gravity represents a conservative force, associated with gravitational potential energy, whereas air resistance is a non-conservative force, associated with dissipated work. Therefore, the work done by gravity is positive and work done by air resistance is negative. Therefore, the correct answer is B.
(AB) & (CD)
Most machines are fueled by gasoline and electricity
Answer:
--->
Explanation:
1. Air Resistance- this is a type of frictional force that acts upon objects as they travel through air. It usually opposes the motion of an object and it is mathematically difficult to predict its value.
2. Gravity- the force of gravity is the force that the earth, and moon use to attract an object towards itself. The moon has far less gravity than earth. All objects on earth experience a force of gravity that pulls them downward, towards the center of the earth.
3. Tension- the tension force is the force that is transmitted through a string, rope, cable or wire when it is pulled from opposite ends. The tension force is directed along the length of the wire and pulls equally on the objects on the opposite ends of the wire
4. Friction- this is the force exerted by a surface when an object moves across it. Friction results from the two surfaces being pressed together closely.
5. Electromagnetic force- although they don't seem similar, electricity and magnetism are related. Flowing electrons produce magnetism, and a moving magnet produces electricity.
6. Upthrust- this is the upward force that a liquid or gas exerts on a body floating in it.
7. Spring force- The spring force is the force exerted by a compressed spring upon any object that is attached to it. This object is always acted upon by a force that restores the object to its rest or equilibrium position.
8. Applied force- An applied force is a force that is applied to an object by a person or another object.
9. Electrostatic force- The types of forces exerted by all electrically charged bodies on another charged bodies in the universe are ‘electrostatic forces’. They can be either positively or negatively charged.
10. Nuclear force- these are the forces that act between two or more nucleons. They bind protons and neutrons into atomic nuclei. The nuclear force is about 10 millions times stronger than the chemical binding that holds atoms together in molecules.
Answer:C..net work done on the object.
Explanation:
Answer:
1160 ohm
Explanation:
We are given that
R'=580 ohm
Current=3 I
We have to find the resistance of the circuit.
Let R be the resistance of circuit.
In parallel
Using the formula
In parallel combination,Potential difference across each resistance remains same.
Using the formula