Hey there, Class 11 students! If you're diving into the world of physics, we've got something cool for you. We've just put up brand-new questions for you to practice on our blogger website. These questions are like a sneak peek of what you might see in your exams.
1) A value for the acceleration of free fall on Earth is given as (20士2)m/s².Which statement is correct?
a) The value is accurate but not precise
b) The value is both accurate and precise
c) The value is neither precise or accurate
d) The value is precise but not accurate.
Answer: a)The value is accurate but not precise
The True value of the acceleration of free fall is 9.81m/s²
Now acceleration of free fall can be form (10-2)=8m/s² to (10+2)=12m/s²
The actual true value 9.8 lies within the range given by the uncertainty, and therefore the stated value is accurate. [C and D are incorrect]
Precise deals with how small or large the uncertainty is. A precise set of measurements would have a small scatter of readings.
Here, the value is Not precise as the uncertainity is large (relative to the mean value of 10)
Percentage uncertainty = 2/10 * 100% = 20% (This is rather large)
2) Which of the following is not a vector quantity?
a)torque
b)energy
c)angular momentum
d)electric field intensity
Answer: b)energy
Energy is not a vector quantity because energy has not any direction.
2)A constant force pushes a block along a horizontal frictionless surface. The block moves from rest through a fixed distance. What is the relationship between the final speed v of the block and its mass m?
a) √v ∝ 1⁄m
b)√v ∝ √m
c)√v ∝ 1⁄√m
d)√v ∝ m
Answer: c)√v ∝ 1⁄√m
v²=u²+2as
Since the block moves from rest, u=0
v²= 2as
Since a constant force is applied, F=ma, giving a=F/m
So, acceleration a ∝1/m
Replacing the relationship a ∝1/m into the equation involving velocity
v ² ∝ 1/m
√v ∝ 1⁄√m
3) A car has a mass m. A person needs to push the car with a force F in order to give the car acceleration a. The person needs to push th car with a force 2F in order to the car acceleration 3a. Which expression gives the constant resistive force opposing the motion of the car?
a) ma
b) 2ma
c) 3ma
d) 4ma
Answer: ma
4)Which graph represents the motion of a car that is travelling along a straight road with a increase uniformly with time?
Answer: A
We need to look at the exes carefully in each graph so that we can know which quantities are involved and which other quantities may be obtained from the gradient or area under graph.
Travelling along a straight road with a speed that increases uniformly with time means that there is a uniform acceleration that is the acceleration is constant; the acceleration is not changing.
Graph A: acceleration-time graph - Acceleration has a constant value
Graph B: acceleration-time graph - Acceleration is increasing from a non-zero value
Graph C: displacement-time graph - straight line with a positive gradient- Velocity is constant
Graph D: displacement-time graph- horizontal line i.e velocity is 0
5) Work done by frictional force is
a) zero
b) negative
c) positive
d) infinity
Answer: b)
Frictional force is always opposing the relative motion of the body. When a body is dragged along a rough surface, the frictional force will be acting in the direction opposite to the displacement. Thus, the work done by the frictional force will be negative.
6) The working principle of a rocket is based on the principle of conservation ofa) velocityb) forcec) linear momentumd) friction
Answer: c)The principle of rocket propulsion works on the 'Newton's Third Law of Motion'. It states that, 'to every action, there is always an equal and opposite reaction'.In the case of a rocket, the engine emits hot burning gases in the downward direction. These gases apply an equal and opposite reaction force to the rocket in the upward direction.This is how a rocket is propelled.The principle of conservation of momentum states that whenever two bodies collide or get separated, then their total momentum before collision or separation is equal to their total momentum after collision or separation.Since the gases of the rocket and the rocket are stationery at the start, their total momentum is zero. After the gases start burning, the momentum imparted to the rocket is equal and opposite to that of the gases. Hence their total momentum is zero.
7) The field of view is minimum fora) concave mirrorb) convex mirrorc) plane mirrord) parabolic mirror
Answer: a)
The field of view is minimum for concave mirror because they are converging mirrors.
8) For a minimum deviation of light inside the prism the angle of emergence should be equal toa) angle of prismb) angle of incidencec) angle of refractiond) angle of deviation.
Answer: b)
i=e for minimum deviation
9) If we put an object at the focus of a convex lens, the refracted rays area) parallelb) convergingc) divergingd) both converging and diverging
Answer: d) both converging and diverging 10) The resistance of a wire is R. If the length of the wire is doubled by stretching, then the new resistance will bea) 2Rb) 4Rc) Rd) R/4
Answer: b)
As the length of wire gets doubled, the cross-sectional area will become half of its previous value because volume of wire remains constant. Hence, we can see that the new resistance is four times the previous resistance.
11) What are the elementary particles with half spin called?a) quarkb) fermionsc) bosonsd) hadrons
Answer: Fermions
In the case of a rocket, the engine emits hot burning gases in the downward direction. These gases apply an equal and opposite reaction force to the rocket in the upward direction.
This is how a rocket is propelled.
The principle of conservation of momentum states that whenever two bodies collide or get separated, then their total momentum before collision or separation is equal to their total momentum after collision or separation.
Since the gases of the rocket and the rocket are stationery at the start, their total momentum is zero. After the gases start burning, the momentum imparted to the rocket is equal and opposite to that of the gases. Hence their total momentum is zero.
7) The field of view is minimum for
a) concave mirror
b) convex mirror
c) plane mirror
d) parabolic mirror
Answer: a)
The field of view is minimum for concave mirror because they are converging mirrors.
8) For a minimum deviation of light inside the prism the angle of emergence should be equal to
a) angle of prism
b) angle of incidence
c) angle of refraction
d) angle of deviation.
Answer: b)
i=e for minimum deviation
9) If we put an object at the focus of a convex lens, the refracted rays are
a) parallel
b) converging
c) diverging
d) both converging and diverging
Answer: d) both converging and diverging
10) The resistance of a wire is R. If the length of the wire is doubled by stretching, then the new resistance will be
a) 2R
b) 4R
c) R
d) R/4
Answer: b)
As the length of wire gets doubled, the cross-sectional area will become half of its previous value because volume of wire remains constant. Hence, we can see that the new resistance is four times the previous resistance.
11) What are the elementary particles with half spin called?
a) quark
b) fermions
c) bosons
d) hadrons
Answer: Fermions
GROUP – B: Short Answer Questions [8×5=40]
GROUP – B: Short Answer Questions [8×5=40]
1. An aircraft is at rest at one end of a runway which is 2.2Km long. The aircraft
accelerates along the runway with an acceleration of 2.5ms−2 until it reaches its
take-off speed of 75m/s. Calculate
a) the time taken to reach take off speed (1)
b) the distance travelled in this time. (1)
c) Just as the aircraft reaches take-off speed a warning lights on. The maximum
possible deceleration of the aircrafts is 4 ms−2 and 2.5 s elapses before the
pilot takes any action during which times the aircraft continues at its take off
speed. Determine whether or not the aircraft can be brought to rest in the remaining length of run way.
OR
a) Bridges are declare unsafe after long use why? (2)
b) The elastic limit of steel is 8× 108Nm−2 and Young’s modulus is 2× 1011Nm−2 .Calculate the maximum elongation of a half-meter steel wire that can be given without exceeding the elastic limit. (2)
c) Do liquid posses rigidity? What is the value of modulus of rigidity for liquid? (1)
2. a) On a hot day, sweats forms on the surface of the boy body and evaporates Explain how this process helps the body to cool down. (2)
b) The temperature of a person of mass 60Kg falls from 37.2 0C to 36.7 0C. Calculate the energy lost from body. The average specific heat capacity is 4000J/kg0C. (2)
c) Calculate the mass of sweat which evaporated. The specific latent heat
vaporization of sweat is 2.4× 106 J/kg. (1)
3. a) Why are the two think blankets warmer than a single blanket of double the
thickness?
b) Estimate the rate of heat loss through a glass window of area 2m2 and
thickness 3mm when the temperature of the room is 200C and that of the air outside is 50
. (3)
4. a) Write down the postulates of kinetic theory of gas. (3)
b) Under what condition do the real gases obey more strictly the gas equation?(2)
5. a) Can a convex mirror form a real image? (2)
b) A 450 − 450 − 900 glass prism is immersed in a water. Calculate the minimum value of refractive index of the prism may have if it is to totally reflect a ray incident normally on of its shortest faces .
OR
a) What will happen if lens is immersed in a liquid whose absolute refractive
refractive index is equal to that of the lens? (2)
b) The real image obtained by lens of power 5D is three times the object. Calculate the object and image distances. (2)
c) Will its power increases or decreases if lens in (b) is immerged into water. (1)
6. a) Charge is considered as derived quantity Why? (1)
b) Two isolated electrons are separated in vacuum by a distance x compare the electric force between the two electron and the gravitational force between the two electrons. (3)
b) By reference to your answer in (a) suggest why gravitational force are not considered when calculating the force between the charged particles. (1)
7. An electric heater is made of from nichrome wire. Nichrome has a resistivity of
1.0× 10−6 Ωm at the operating temperature of the heater. The heater is to have a
power dissipation of 60W when the potential difference across its terminal is 12 V
a) State what do you mean by electric current. (1)
b) Calculate the length of nichrome wire of a diameter is 0.80 mm required for the heater. (2)
c) A second heater, also designed to operate from a 12V supply is constructed using same nichrome wire but half the length of that calculated in (a)Explain, the effect of this change in length of wire on power of heater. (2)
8. The diagram shows a graph of charge against voltage for a capacitor.
a) What is represented by the slope of the graph? (1)
b) What quantity is represented by the shaded area? (1)
c) An electronic camera flash guns contain a capacitor of 100μF which is charged to a
voltage of 250 V. Show that energy stored is 3.1J. (3)
GROUP – C: Long Answer Questions [3×8 = 24]
9). A bullet of mass 2 g is fired horizontally into a block of wood of mass 600g the block is suspended from strings so that it is free to move in a vertical plane. The bullet buries itself in the block. The block and bullet rise together through vertical distance of 8.6cm as shown in figure.
a) Calculate the change in gravitational potential energy of the block and bullet. (2)
b) Determine the speed of bullet of bullet before the impact. (2)
c) Calculate the kinetic energy of the bullet just before the impact. (2)
d) Explain what can be deduced from your answer in a and c about the type of
collision between the bullet and the block. (2)
10. a) Explain why values of gravitational potential near to an isolated mass are all negative. (2)
b) The earth may be assumed to be an isolated sphere of radius 6.4× 103 Km with its mass of 6.0× 1024Kg concentrated to its centre. An object is projected vertically from the surface of the Earth so that it reaches an altitude of 1.3× 104Km. Calculate for this object
i. the change in gravitational potential. (2)
ii. the speed of projection from the Earth surface assuming air resistance is negligible. (2)
c) Suggest why the equation v2 = u2 + 2as is not appropriate for the calculation in b (ii). (2)
OR
a) The acceleration of a body moving in a circular path remains constant? (2)
b) A large bowl is made from a part of hollow sphere. A small spherical ball is placed inside
the bowl and is given a horizontal speed. The force follows a horizontal circular path of
constant radius as shown in figure
c) The forces acting on the ball are its weight W and the normal reaction force R of the bowl on the ball, as shown in figure.
The normal reaction force R is at right angle θ to the horizontal.
i) By resolving the reaction force R into two perpendicular components, show the resulatant force F acting on the ball
ii) State the significance of the force F for the motion of the ball in the bowl.
c) The ball moves in a circular path of radius 14cm.For this radius, the angle θ is
280. Calculate the speed of the ball .
11. a) Show that the energy equivalent to 1amu is 931Mev. (2)
b) Why do stable nuclei have more neutrons than protons? (2)
c) Can a hole created in a metal? (2)
d) There are equal number of free electrons with holes in the pure semiconductor Why don’t they cancel each other by giving no electric current when a battery is connected across the two ends of the semi-conductor? (2)
If you have any doubts, Please let me know