Answer:
C. A rubber rod and a glass rod charged this way have opposite charges on them.
Explanation:
When a rubber rod is rubbed against cat fur, it acquires a negative charge, it becomes negatively charged.
When you then try to bring two rubber rod's together, they repel because like charges repel.
Meanwhile, when you rub a glass rod against silk, it loses electrons to the silk material and becomes positively charged.
When you bring two positively charged glass rod's together, they repel, because like charges repel.
However, when you bring the rubber rod and a glass rod together, the attract each other because unlike/opposite charges attract.
This question can be solved using the concept of friction energy.
The thermal energy change is b "258.4 J".
The change in thermal energy will be equal to the friction energy produced during the motion of the box.

where,
μ = coefficient of kinetic friction = 0.4
f = force applied = 38 N
d = distance traveled by the box = 17 m
Therefore,

<u>E = 258.4 J</u>
Learn more about friction energy here:
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The answer is high temperatures
Answer:
Explanation:
The person will have normal eye if he can see objects placed even at infinite
distance. He suffers from short shortsightedness. He can not see beyond 80 cm. He requires diverging lens ( concave lens ) the focal length of which will be 80 cm , because in that case, light coming from infinity will appear to be coming from 80 cm so he can see them.
Focal length in cm = - 80cm
Power =- 100/80 D = -1.25 Diopters