Question

Que. 8.
If A + B = C then prove that
C = √(A +B +2AB Cos teeta) where teeta is angle between A and B

Que. 9.
A force F = i + 5j +7k acts on particle and displaces it through S=6i+ 9k
calculate the work done it force is in Newton and displacement in meter.

Or

If a force of 2i+5j displaces a body from (2.1,1) to (1,2,3), find the worked done

Que. 10.
Two balls each of mass 0.06 kg imoving in opposite direction with a speed 5 m/s
collide and rebound with the same speed, what is impulse imparted to each ball due to
other.

Que. 11.
A disc of mass 5 Kg and radius 50 cm rolls on the ground at the rate of 10 m/s
calculate the Kinetic Energy of Disc (Given I=1/2 MR'2)
Que. 12.
If length of a pendulum of wall clock is increased by 0.1%, then find error in time per
day.
Que. 13. The efficiency of an ideal engine is 1/8 By lowering the temperature of sink by look, it
increases to 1/4 .Find the initial and final temperature of sink.
Que. 14.
What is the modulus of elasticity? For a given material what are the different
types of modulus of elasticity depending upon types of stress applied and type of strain
produced.
Que. 15.
Define elastic and inelastic collisions A lighter body collides with a much more
massive body at rest, prove that the direction of lighter body is reversed and massive
body remains at rest.
​

Answer 1

8. question should be that if A vector + B vector = C vector then prove

$\sqrt{a {}^{2} + b {}^{2} + 2abcos \alpha }$

If it's not that then

$(a + b) = c \\ (a + b) {}^{2} = c {}^{2} \\ c = \sqrt{a {}^{2} + b {}^{2} + 2ab \cos(0) }$

9.F=I+5j+7k

S=6i + 9k

W = F.S

W =6+63=69

11.Kinetic Energy = 1(I.W^2÷2)

E= 125÷16 = 7.7kgm^2.rad^2sec^-2