CBSE 11TH PHYSICS - Online Test
Q1. The kinetic energy of a body executing S.H.M. is 1/3 of the potential energy. Then, the displacement of the body is x percent of the amplitude, where x is
Answer : Option D
Explaination / Solution:
No Explaination.
Q2. in which of the following examples of motion, can the body be considered approximately a point object?
Answer : Option C
Explaination / Solution:
Point object is an expression used in kinematics branch of physics: it is an object whose dimensions are ignored or neglected while considering its motion.
The size of a carriage is very small as compared to the distance between two stations. Therefore, the carriage can be treated as a point sized object.
Q3. The human ear is most sensitive to sound in the frequency range of
Answer : Option A
Explaination / Solution:
No Explaination.
Q4. If the radius of earth reduces by 4% and density remains same then escape velocity will
Answer : Option C
Explaination / Solution:
Escape velocity ve α Rρ−−√and if density remains constant⇒ve α RSo if the radius reduces by 4% then escape velocity also reduces by 4%
Q5. A passenger arriving in a new town wishes to go from the station to a hotel located 10 km away on a straight road from the station. A dishonest cabman takes him along a circuitous path 23 km long and reaches the hotel in 28 min. What is (a) the average speed of the taxi, (b) the magnitude of average velocity?
Answer : Option D
Explaination / Solution:
(a) Total distance travelled = 23 km
Total time taken = 28 min = h
∴ Average speed of the taxi =
(b) Distance between the hotel and the station = 10 km = Displacement of the car
∴ Average velocity =
Q6.
A steel wire of length 4.7 m and cross-sectional area 3.0 stretches by the same amount as a copper wire of length 3.5 m and cross-sectional area of 4.0 under a given load. What is the ratio of the Young’s modulus of steel to that of copper?
Answer : Option D
Explaination / Solution:
No Explaination.
Q7.
A geyser heats water flowing at the rate of 3.0 liters per minute from 27 C to 77 C. If the geyser operates on a gas burner, what is the rate of consumption of the fuel if its heat of combustion is 4.0 J/g?
Answer : Option B
Explaination / Solution:
m = mass of water
s = specific heat of water
heat of combustion is 4.0 J/g
rate of consumption of the fuel = Q / Heat of combustion
Q8. The casing of a rocket in flight burns up due to friction. At whose expense is the heat energy required for burning obtained?
Answer : Option A
Explaination / Solution:
Heat energy required for burning of casing of rocket comes from the rocket itself. As a result of work done against friction the kinetic energy of rocket continuously deceases and this work against friction reappears as heat energy. This results in reduction of the mass of the rocket.
Q9. One end of a string of length l is connected to a particle of mass m and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed v, T is the tension in the string, the net force on the particle directed towards the centre is
Answer : Option A
Explaination / Solution:
According to Newton's third law of motion, the net force on a rotating particle is equal to Tension in the String. As the action (ie force towards the centre) and reaction (tension in the string) are equal in magnitude and opposite in direction.
Q10. Technology started with
Answer : Option B
Explaination / Solution:
The history of technology is the history of the invention of tools and techniques and is similar to other sides of the history of humanity. Technology can refer to methods ranging from as simple as language and stone tools to the complex genetic engineering and information technology that has emerged since the 1980s.
