Question

The
frictional force exerted by fluids is called

(a) drag

(b) sliding friction.

(d) none of these

(c) rolling friction. Friction between two 2

flat surfaces cannot be reduced by (b) polishing,

(a) greasing (c) using ball bearing

(d) decreasing the area.

3. Rolling friction is always less than the

(b) static friction

(d) fluid friction

(a) sliding friction. (c) both (a) and (b).

4 Which of the following is not an effect of friction?

(a) Moving objects slow down (c) Moving objects wear off

(b) Moving objects stop (d) Moving objects have w

5 A flying machine offering the least frictional force should be (b) tree-like

(a) irregular.

(c) symmetrical with many arms. 6. Lubrication of the moving surfaces

(d) streamlined.

6) lubrican of the moving surface

(a) removes friction.

(c) increases friction

(b) reduces friction.

(d) has no effect on frictic​

Answer 1

Answer:

PQRS is a rhombus with ∠PQR=58∘ . ... Hint: The quadrilateral having all sides of equal length is called rhombus. The adjacent sides of a rhombus are supplementary.