Subject :NSO Class : Class 8
Which of the following statements is/are correct?
(A) To increase the stability of a ship the base area
must be made large.
(B) A cone which is resting on its apex is an example
of unstable equilibrium.
(C) The momentum of a body is the product of mass and velocity of the body.
(D) Frictional force always acts in a direction
opposite to the direction of motion.
A(A) and (B)
B(A), (B) and (C)
C(B) and (C)
DAll of these
Frictional force acts relativly opposite to the direction of motion Isnt the answer B then ?
Ans 1:
Class : Class 8
In my opinion, the answer to this question should be option (B), instead of option (D). According to option (D), the statement - (D), is correct. However, it is not nearly correct. Frictional force doesn't always act in a direction opposite to the direction of motion. There are many exceptions to this case. For example: A car's wheels turning to push back on the road experiences a forward friction that helps it move, a person's leg pushing back on the pavement experiences a forward friction that helps him/her to walk, etc. Thus, relative to a fixed point, friction can also help to support overall motion. So, statement (D) is incorrect. The statement: "Frictional force always acts in a direction opposite to the direction of 'relative' motion." would be more correct, as from the fixed point of motion, friction will always oppose the relative motion of a body.