ANNUAL EXAM PAPER 2019 PHYSICS CLASS 11 SECTION 'A' and 'B' (SOLUTION FULLY EXPLAINED)

Class XI
Annual Exam - 2019
(solved Paper)

Section A and Section B

1. What will be the effect on maximum height of a projectile when its angle of projection is changed from 30⁰ to 60⁰ , keeping the same initial velocity of projection?

Solution: 

2. A body is moving along a circular path. How much work is done by the centripetal force?

Solution: While moving in a circular path, the required centripetal force always acts radially inwards i.e. in a direction perpendicular to the direction of motion. As a result the work done by this centripetal force will be zero because 

                    W= Fscosθ = Fscos90⁰

^{3. Where does the center of mass of a uniform triangular lamina lie?}

^{Solution: The center of mass of a uniform triangular lamina lies at the centroid of the triangle.}

^{4. Define elastomers with example.}

^{Solution: Elastomers are those materials which dooes not obey Hooke's law and does not have a well defined plastic region. e.g. Rubber}

^{5. On an average a human heart is found to beat 75 times in a minute. Calculate frequency.}

^{Solution: Human Heart beats 75 times in a minute} 

                     ^{frequency = no. of beats/second}

                                       ^{f = 75/60}

                                       ^{f = 1.25 Hz}

^{6. Each side of a cube is 7.203m. Calculate surface area and volume of cube upto correct no. of significant figure.}

^Solution: 

^{7. Show that trajectory of a projectile at angle θ with horizontal is parabolic in nature.}

^{Solution: Consider an object projected from the origin with a velocity u, making an angle θ with the horizontal. suppose at any time t object reaches P} 

8. What are impulsive forces? Give example.

Solution: Impulsive forces are the forces that acts on a body for a short interval of time making a change in its velocity e.g. when a batsman hits a ball a force acts on the ball for a short interval of time this force is called impulsive force.

OR

 Using Newton's second law of motion deduce first law of motion.

Solution: 

9. A ball is thrown vertically upwards with a velocity of 20 m/s from the top of a multi-storey building. The height of the point from where the ball is thrown is 25.0 m from the ground.

a) How high will the ball rise?

b) How long will it take to reach the ground?

Solution: 

10. The flow rate of water from a tap of diameter 1.25 cm is 0.48L/min. The coefficient of viscosity of water is 10^-3 Pa-s. After sometimes the flow rate is increased to 3L/min. Characterize the flow for both the flow rates.

Solution: 

11. A thermodynamic system is taken from original state D to an intermediate state E by  a linear process shown in figure. Its volume is then reduced to the original value from E to F by an isobaric process. Calculate the total work done by the gas from D to E and E to F.

Solution: 

12. This question is not from your syllabus for current Year