Fill in the blanks: (a) A stone tied to a string is rotated in a horizontal plane. The tension in the string provides the __________ force necessary for circular motion. (b) The work done by this force at any instant is __________.

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

When a bell fixed on a cycle rings, then the energy conversion that takes place is: (a) gravitational potential energy to sound energy (b) kinetic energy to sound energy (c) sound energy to electrical energy (d) sound energy to mechanical energy

(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.

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) 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?

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

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

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?

Complete the following by choosing the correct answers from the bracket: (a) In uniform circular motion the centrifugal force acts ............... [towards the centre/away from the centre/along the tangential direction]. (b) Refractive index of a medium is independent of ............... [temperature/angle of incidence/wavelength of light]. (c) Heat absorbed during change of phase depends on ............... [mass/change in temperature/specific heat capacity] of the substance. (d) Emf of a cell is ............... [greater than/less than/equal to] the terminal voltage when the cell is in open circuit. (e) In a step-up transformer the turns ratio is ............... [more than 1/less than 1/equal to 1]. (f) The nuclear radiation with lowest ionising power is ............... [α/β/γ].

Which among the following is a vector quantity? (a) work (b) power (c) energy (d) moment of couple