A. s.a. p.! will be marked to be as ! 30 !

kennedy and lilly are in science class. they are asked to prove that some forces are non-contact forces. the girls list five examples of objects exerting a force on each other without touching. do you agree with their list? tell why or why not?

1) two like magnetic poles repel each other.

2)putting on a wool sweater can make your hair get static electricity when it rubs against the sweater.

3) when you bring two negatively charged balloons near each other they push each other away.
4) magnets stick to a refrigerator.

5) a motor uses magnets to transform mechanical energy into electrical energy.

a)number 1 and 4 are non-contact forces since they both use magnets.

b)number 1, 3 and 5 all demonstrate non-contact forces because the magnets or electrically charged objects exert forces on each other without touching.

c)all five are good examples of non-contact forces since they all use either magnets or electric charge which are non-contact forces.

d)number 1 and 3 are both good examples to prove non-contact forces since the magnets and balloons are not touching.

B)Number 1, 3 and 5 all demonstrate non-contact forces because the magnets or electrically charged objects exert forces on each other without touching.

Explanation:

Forces which act only when the two surfaces are in contact are known as contact forces. For example: frictional force is a contact force because it acts only when the two surfaces have tendency to move or are in relative motion.

Forces which act without any contact between surfaces are non-contact forces. For example: magnetic force, gravitational force, electrical force.

Because Kennedy and Lilly have to prove that some forces are non-contact forces, they must put up examples which actually show force being exerted between two objects without they being in contact. Thus, number 1, 3 and 5 demonstrate this.

B)Number 1, 3 and 5 all demonstrate non-contact forces because the magnets or electrically charged objects exert forces on each other without touching.

Explanation:

Forces which act only when the two surfaces are in contact are known as contact forces. For example: frictional force is a contact force because it acts only when the two surfaces have tendency to move or are in relative motion.

Forces which act without any contact between surfaces are non-contact forces. For example: magnetic force, gravitational force, electrical force.

Because Kennedy and Lilly have to prove that some forces are non-contact forces, they must put up examples which actually show force being exerted between two objects without they being in contact. Thus, number 1, 3 and 5 demonstrate this.

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Explanation:

d) the number of neutrons plus the number of protons