Complete the following by choosing the correct answers from the bracket: (a) A car is moving in uniform circular motion. The direction of friction between the tyres and the path is ............... [towards the centre / tangential to the path]. (b) When a ray of light passes from a denser to a rarer medium, its wavelength ............... [decreases / increases]. (c) The lid of a calorimeter minimises heat loss by ............... [convection / radiation]. (d) Quality of sound depends on its ............... [amplitude / waveform]. (e) A substance whose resistance becomes almost negligible at a temperature near absolute zero is called a ............... [semiconductor / superconductor]. (f) ............... radiation deviates minimum in a magnetic field [Alpha / Beta].

State two factors on which the position of Center of Gravity of a body depends.

For a body to be in dynamic equilibrium: (a) its momentum must be zero (b) its acceleration must be zero (c) its kinetic energy must be zero (d) its velocity must be zero

A metre scale of weight 50 gf can be balanced at 40 cm mark without any weight suspended on it. (a) If this ruler is cut at its centre then state which part [0 to 50 cm or 50 to 100 cm] of the ruler will weigh more than 25 gf. (b) What minimum weight placed on this metre ruler can balance this ruler when it is pivoted at its centre?

(a) Define Centre of Gravity. (b) A hollow ice cream cone has height 6 cm. (i) Where is the position of its centre of gravity from the broad base? (ii) Will its position change when it is filled completely with honey? Write Yes or No.

Akash takes a uniform metre scale and suspends a weight of 2 N at one end ‘X’, and a weight of 5 N on the other end ‘Y’. He then balances the ruler horizontally on a knife edge placed at 70 cm from X. Draw a diagram of the arrangement and calculate the weight of the ruler.

A non-uniform kite is hanging freely from the branch of a tree as shown. Study the figure and answer the following: (a) Fill in the blank. ............... [P, Q, R or S] is the most probable position of its centre of gravity. (b) Support your answer to (a) with a reason.

The diagram shows wheel O pivoted at point A. Three equal forces F1, F2 and F3 act at point B on the wheel. (a) Which force will produce maximum moment about A? (b) Give a reason for your answer in (a).

A non-uniform beam of weight 120 N pivoted at one end is shown in the diagram below. Calculate the force F required to keep the beam in equilibrium.

A door lock is opened by turning the lever (handle) of length 0.2 m. If the moment of force produced is 1 Nm, then the minimum force required is: (a) 5 N (b) 10 N (c) 20 N (d) 0.2 N

(a) What is the position of centre of gravity of a triangular lamina? (b) When this triangular lamina is suspended freely from any one vertex, what is the moment of force produced by its own weight in its rest position?

Clockwise moment produced by a force about a fulcrum is considered to be: (a) Positive (b) Negative (c) Zero (d) None of these