Oscillations — Physics STD 11 Science — Question

Ultrasonic waves of frequency 4.5MHz are used to detect tumour in soft tissues. The speed of sound in tissue is 1.5km/s and that in air is 340m/s. Find the wavelength of this ultrasonic wave in air and in tissue.

A particle of mass 100g is kept on the surface of a uniform sphere of mass 10kg and radius 10cm. Find the work to be done against the gravitational force between them to take the particle away from the sphere.

A body has a sense of weightlessness in a satellite revolving around the earth, why?

What is an elastomer? What are their special features?

An object moves in simple harmonic motion with an amplitude of 5 cm and a frequency of 0.2 sec . Find the acceleration and velocity of the object when the displacement of the object is (a) 5 cm (b) 3 cm (c) 0 cm .

Explain why:
A body with large reflectivity is a poor emitter.

Metallic (nonferromagnetic) and nonmetallic particles in a solid waste may be separated as follows. The waste is allowed to slide down an incline over permanent magnets. The metallic particles slow down as compared to the norunetallic ones and hence are separated. Discuss the role of eddy currents in the process.

Two heavy spheres each of mass 100 kg and radius 0.10 m are placed 1.0 m apart on a horizontal table. What is the gravitational force and potential at the midpoint of the line joining the centres of the spheres? Is an object placed at that point in equilibrium? If so, is the equilibrium stable or unstable?

Plot Load vs Extension curve for a metal on the graph and depict:

1. Yield point.
2. Breaking point.
3. Elastic limit.
4. Crushing point.