i) Why does a bottle of soft drink cool faster when surrounded by ice cubes than by ice cold water, both at 0^o C.

32.

A calorimeter of mass 50 g and specific heat capacity 0.42 J g^-1oC^-1 contains some mass of water at 20^o C. A metal piece of mass 20 g at 100 degree C is dropped into the calorimeter. After stirring, the final temperature of the mixture is found to be 22^o C. Find the mass of water used in the calorimeter.

Which of the radioactive radiations:

i) can cause severe genetic disorders?

A radioactive nucleus undergoes a series of decays according to the sequence: 



If m is the mass number and atomic number of X₃ are 172 and 69 respectively, what is the mass number and atomic number of X?

Name the radiations:

i) Used for photography at night.

ii) Used for detection of fracture in bones.

iii) Whose wavelength range is from 100 

Name the three main parts of a Cathode Ray Tube

i) What is meant by radioactivity?

ii) What is meant by nuclear waste?

A coolie is pushing in a box weighing 1500 n up an inclined plane 7.5 m long on to a platform 2.5 m above the ground,

i) Calculate the mechanical advantage of the inclined plane.

ii) Calculate the effort applied by the coolie.

A block and tackle system of pulleys has a velocity ratio 4.

i) Draw a labelled diagram of the system indicating clearly the points of applications and direction of load and effort.

i) What is meant by the term:

1. Amplitude 2. Frequency, of a wave?