Physics
(a) A force applied on a
I. rigid body
II. non-rigid body
How does the effect of force differ in the two cases?
(b) Give one example of couple force.
Answer
(a) (i) Rigid body — A force when applied on a rigid object does not change the inter-spacing between it's constituent particles and therefore it does not change the dimensions of the object, but causes only motion in it.
(ii) Non-rigid body — A force when applied on a non-rigid object, changes the inter-spacing between it's constituent particles and therefore causes a change in it's dimensions and can also produce motion in it.
(b) Two equal and opposite parallel forces, not acting along the same line form a couple. E.g. tightening the cap of a bottle.
Related Questions
A linear object is placed on the axis of a lens. An image is formed by refraction in the lens. For all positions of the object on the axis of the lens, the positions of the image are always between the lens and the object.
(a) Name the lens.
(b) Draw a ray diagram to show the formation of the image of an object placed infront of the lens at any position of your choice except infinity.
Draw ray diagrams showing the image formation by a convex lens when an object is placed
(a) between optical centre and focus of the lens.
(b) between focus and twice the focal length of the lens.
(c) at twice the focal length of the lens.
(d) at infinity.
(a) In a single movable pulley, if the weight of the load is L and the weight of the movable pulley is w, find out the expression for its mechanical advantage.
(b) Which simple machine is used by labourers to load heavy barrels on a truck?
(c) Does a single fixed pulley help us to multiple force? In what way is it useful?
(a) A runner of mass 60 kg runs upstairs and reaches the 10 m high first floor in 4 s.
Calculate the
I. force of gravity acting on him
II. work done by him against gravity and
III. power developed by the runner.
(b) Give two examples in which mechanical energy is conserved.