Science (English Medium) Class 11 - CBSE Question Bank Solutions

A satellite is in an elliptic orbit around the earth with aphelion of 6R and perihelion of 2 R where R= 6400 km is the radius of the earth. Find eccentricity of the orbit. Find the velocity of the satellite at apogee and perigee. What should be done if this satellite has to be transferred to a circular orbit of radius 6R ?

[G = 6.67 × 10^–11 SI units and M = 6 × 10²⁴ kg]

Pressure is a scalar quantity because ______.

1. it is the ratio of force to area and both force and area are vectors.
2. it is the ratio of the magnitude of the force to area.
3. it is the ratio of the component of the force normal to the area.
4. it does not depend on the size of the area chosen.

Iceberg floats in water with part of it submerged. What is the fraction of the volume of iceberg submerged if the density of ice is ρ_i = 0.917 g cm^–3?

A vessel filled with water is kept on a weighing pan and the scale adjusted to zero. A block of mass M and density ρ is suspended by a massless spring of spring constant k. This block is submerged inside into the water in the vessel. What is the reading of the scale?

The equation of motion of a particle is x = a cos (αt)². The motion is ______.

The displacement time graph of a particle executing S.H.M. is shown in figure. Which of the following statement is/are true?

1. The force is zero at `t = (T)/4`.
2. The acceleration is maximum at `t = (4T)/4`.
3. The velocity is maximum at `t = T/4`.
4. The P.E. is equal to K.E. of oscillation at `t = T/2`.

What are the two basic characteristics of a simple harmonic motion?

Show that the motion of a particle represented by y = sin ωt – cos ωt is simple harmonic with a period of 2π/ω.

A person normally weighing 50 kg stands on a massless platform which oscillates up and down harmonically at a frequency of 2.0 s^–1 and an amplitude 5.0 cm. A weighing machine on the platform gives the persons weight against time.

1. Will there be any change in weight of the body, during the oscillation?
2. If answer to part (a) is yes, what will be the maximum and minimum reading in the machine and at which position?

A person normally weighing 50 kg stands on a massless platform which oscillates up and down harmonically at a frequency of 2.0 s^–1 and an amplitude 5.0 cm. A weighing machine on the platform gives the persons weight against time.

1. Will there be any change in weight of the body, during the oscillation?
2. If answer to part (a) is yes, what will be the maximum and minimum reading in the machine and at which position?

The sign of work done by a force on a body is important to understand. State carefully if the following quantity is positive or negative:

Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket.

The sign of work done by a force on a body is important to understand. State carefully if the following quantity is positive or negative:

Work done by gravitational force on a man in lifting a bucket out of a well by means of a rope tied to the bucket.

The sign of work done by a force on a body is important to understand. State carefully if the following quantity is positive or negative:

Work done by friction on a body sliding down an inclined plane.

The sign of work done by a force on a body is important to understand. State carefully if the following quantity is positive or negative:

Work done by an applied force on a body moving on a rough horizontal plane with uniform velocity.

The sign of work done by a force on a body is important to understand. State carefully if the following quantity is positive or negative:

Work done by the resistive force of air on a vibrating pendulum in bringing it to rest.

Calculate the force of gravitation between the earth and the Sun, given that the mass of the earth = 6 × 10²⁴ kg and of the Sun = 2 × 10³⁰ kg. The average distance between the two is 1.5 × 10¹¹ m.

Some of the most profound statements on the nature of science have come from Albert Einstein, one of the greatest scientists of all time. What do you think did Einstein mean when he said : “The most incomprehensible thing about the world is that it is comprehensible”?

“Every great physical theory starts as a heresy and ends as a dogma”. Give some examples from the history of science of the validity of this incisive remark

“Politics is the art of the possible”. Similarly, “Science is the art of the soluble”. Explain this beautiful aphorism on the nature and practice of science.

India has had a long and unbroken tradition of great scholarship — in mathematics, astronomy, linguistics, logic and ethics. Yet, in parallel with this, several superstitious and obscurantistic attitudes and practices flourished in our society and unfortunately continue even today — among many educated people too. How will you use your knowledge of science to develop strategies to counter these attitudes ?