Question

9:32 Expert Q&A 8.) Raising a car in a service station requires work. Raising it twice as high requires (a)the same amount of work, but twice the power (b)twice the work (c)twice the power (d) b and c only 9.) To bring a supertanker to a stop, its engines are typically cut off about 25km from the port. Why is it so difficult to stop or turn a supertanker? (a)because of its energy (b)because of its inertia (c)because of its acceleration (d)because of its power 10.) The force of gravity between two planets depends on their (a) masses and distance apart (b) planetary atmosphere (c) rotational motion (d) all of these 11.) When the distance between two stars is reduced by 1 2,the force between them 1 1 (a) decreases by 2 (b) decreases by (c) increases by a factor of 3 (d) increases by a factor of 4 12.)When you brush your hair and scrape electrons from your hair, the charge of your hair is (a)positive (b)negative (c)both of these (d)neither of these

Answer 1

(8) Raising a car twice as high requires twice the work and twice the power. So option (d) is correct.

(9) It is difficult stop or turn a Supertanker because of its huge mass and size which increases its inertia. So option (b) is correct.

(10) Force of gravity between two planets is equal to (Gm1m2/r2) where m1 and m2 are masses of planets and r is distance between the planets. So option (a) is correct.

(11) As force is inversely proportional to square of distance between the stars, when we half the distance , force becomes 4 times. So option (d) is correct.
(12) when we scrape electrons negative charge is removed, hair becomes positively charged for sometime. So option (a) is correct