Question

(a) The diagram below shows a claw hammer used to remove a nail:

 

(i) To which class of lever does it belong ? 

(ii) Give one more example of the same class of lever mentioned by you in (i) for which the mechanical advantage is greater than one. 

(b) Two bodies A and B have masses in the ratio 5:1 and their kinetic energies are in the ratio 125:9. Find the ratio of their velocities.  

(c) (i) Name the physical quantity which is measured in calories 

(ii) How is calorie related to the SI unit of that quantity?  

(d) (i) Define couple. 

(ii) State the SI unit of moment of couple. 

(e) (i) Define critical angle. 

(ii) State one important factor which affects the critical angle of a given medium.

Answer 1

(a) (i) Class One. 

(ii) Shears used for cutting the thin metal sheets. 

(b) Given

Kinetic energy is given by K = 1/2 mv²

Therefore,

 

(c) (i) Heat energy. 

(ii) 1 cal = 4.2 J. 

(d) (i) It is defined as a set of two equal and opposite forces acting along different lines of action. 

(ii) SI unit is N m. 

(e) (i) It is the angle of incidence in the denser medium for which angle of refraction in the rarer medium is 90°. 

(ii) Nature of the two media in contact.