The local charging of the comb is due to induction. The negative object's charge pushes electrons in the comb away from the side close to the charged object causing that part to be positively charged. Note that the comb's net charge is still zero provided it doesn't touch the object. When you move the comb away its electrons will redistribute.
Oil is less dense than water so it tends to float on the top of the water. Hope this Helps!
Answer:
Explanation:
Given data:
Mass of the paper clip, 
Kinetic energy, 
Let the velocity of the paper clip when it is thrown be <em>v</em>.
Thus,
(rounding to nearest tenth)
