Q2. On which one of the following conservative laws, does a rocket work?
(c) Linear momentum
(d) Angular momentum
Q3. If a small raindrop falls through air
(a) its velocity goes on increasing
(b) its velocity goes on decreasing
(c) its velocity goes on increasing for sometime and then becomes constant
(d) it falls with constant speed for sometime and then its velocity increase
Q4. A multimeter is used to measure
(d) All of the above
Q5. An athlete diving off a high springboard can perform a variety of exercises in the air before entering the water below. Which one of the following parameters will remain constant during the fall?
(a) The athlete’s linear momentum
(b) The athlete’s moment of inertia
(c) The athlete’s kinetic energy
(d) The athlete’s angular momentum
Q6. The force acting on a particle executing simple harmonic motion is
(a) directly proportional to the displacement and is directed away from the mean position
(b) inversely proportional to the displacement and is directed towards the mean position
(c) directly proportional to the displacement and is directed towards the mean position
(d) inversely proportional to the displacement and is directed away from the mean position
Q7. When a ball drops onto the floor it bounces. Why does it bounce?
(a) The floor heats up on impact
(b) The floor exerts a force on the ball during the impact
(c) The floor is perfectly rigid
Q8. It is difficult to cut things with a blunt knife because
(a) the pressure exerted by knife for a given force increase with increase in bluntness
(b) a sharp edge decreases the pressure exerted by knife for a given force
(c) a blunt knife decreases the pressure for a given force
(d) a blunt knife decreases the area of intersection
Q9. Creation of something from nothing is against the law of
(a) constant proportions
(b) conservation of mass-energy
(c) multiple proportions
(d) conservation of momentum
Q10. The source of the sun’s energy is the process of
(a) photoelectric emission
(b) nuclear fission
(c) nuclear fusion
(d) thermionic emission
S1. Ans. (c)
S2. Ans. (c)
Sol.Rocket works on the principle of conservation of linear momentum.
S3. Ans (c)
Sol.Velocity of raindrop increases until it reaches the terminal velocity.
Sol.When a athlete jumps from the spring board, he curls his body by rolling his arms and legs in. By doing so, he decreases moment of inertial of his body and hence angular speed increases to conserve the angular momentum, as I₁ w₁ = I₂ = constant.
S6. Ans. (c)
Sol.The restoring force actin particle is always proportional to the displacement of the particle from the equilibrium position and is always directed towards the equilibrium position.
S7. Ans. (b)
Sol.When a ball drops on to the floor then floor exerts a force for small time which is equal to change in momentum of the ball.
S8. Ans. (c)
Sol.Pressure = force/area
Bluntness of knife increases area, hence decreases the pressure for a given force.
S9. Ans. (b)
Sol.Creation of something from nothing is against the law of conservation of mass energy.