(a) (i) State and define the SI unit of power. (ii) How is the unit

1.	(a) (i) State and define the SI unit of power. (ii) How is the unit horse power related to the SI unit of power? (b) State the energy changes in the following cases while in use: (i) An electric iron. (ii) A ceiling fan. (c) The diagram below shows a lever in use: (i) To which class of levers does it belong? (ii) Without changing the dimensions of the lever, if the load is shifted towards the fulcrum what happens to the mechanical advantage of the lever?(d) (i) Why is the ratio of the velocities of light of wavelengths 4000Å and 8000Å in vacuum 1:1? (ii) Which of the above wavelengths has a higher frequency? (e) (i) Why is the motion of a body moving with a constant speed around a circular path said to be accelerated? (ii) Name the unit of physical quantity obtained by the formula 2K/V2 where K: kinetic energy, V: Linear velocity.
Answer» (a) (i) The SI unit of power is watt (W). The power of an agent is said to be one watt if it does one joule of work in one second. (ii) 1 hp = 746 W (b) (i) Electrical into heat energy (ii) Electrical (c) (i) Second class . (ii)It increases (d) (i) Because all wavelengths of light travel with the same velocity in vacuum (ii) 4000 Å (e) (i) Because at every point of motion the direction of speed changes i.e., the body possesses velocity which changes with time. (ii) J s ^-2 m ^-2

(a) (i) State and define the SI unit of power. (ii) How is the unit horse power related to the SI unit of power? (b) State the energy changes in the following cases while in use: (i) An electric iron. (ii) A ceiling fan. (c) The diagram below shows a lever in use: (i) To which class of levers does it belong? (ii) Without changing the dimensions of the lever, if the load is shifted towards the fulcrum what happens to the mechanical advantage of the lever?(d) (i) Why is the ratio of the velocities of light of wavelengths 4000Å and 8000Å in vacuum 1:1? (ii) Which of the above wavelengths has a higher frequency? (e) (i) Why is the motion of a body moving with a constant speed around a circular path said to be accelerated? (ii) Name the unit of physical quantity obtained by the formula 2K/V2 where K: kinetic energy, V: Linear velocity.

Answer»

(a) (i) The SI unit of power is watt (W).

The power of an agent is said to be one watt if it does one joule of work in one second.

(ii) 1 hp = 746 W

(b) (i) Electrical into heat energy

(ii) Electrical

(c) (i) Second class .

(ii)It increases

(d) (i) Because all wavelengths of light travel with the same velocity in vacuum

(ii) 4000 Å

(e) (i) Because at every point of motion the direction of speed changes i.e., the body possesses velocity which changes with time.

(ii) J s ^-2 m ^-2