When a ray of light enters a glass slab, then:

• only the frequency changes

• frequency and velocity change

• frequency does not change

• frequency and wavelength change

A ball is thrown vertically upward from the ground with a speed of 25.2 mls. The ball will reach the highest point of its journey in:

• 5.14 s

• 3.57 s

• 2.57 s

• 1.29 s

One kilowatt hour is equal to:

• 36 x 10³ joule

• 36 x 10⁵ joule

• 10³ joule

• 10⁵ joule

When sound waves are propagated through a medium, the physical quantity/quantities transmitted is/are:

• matter only

• energy only

• energy and matter only

• energy, momentum and matter

Pressure is a scalar quantity because:

• it is the ratio of force to area and both force and area are vectors

• it is the ratio of magnitude of force to area

• it is the ratio of component of force (normal to area) to area

• None of the above

146.

Which one of the following statements is correct?

• The measurement of mass taken by a spring weighing balance is correct at the place where the spring balance is calibrated for

• The measurement of mass taken by a spring weighing balance is correct at all places

• The measurement of mass taken by a spring weighing balance is correct at the places where the acceleration due to gravity is same with the place where the spring balance is calibrated for

• A spring balance cannot be used to measure mass at any place

Which one of the following is not a contact force?

• Push force

• Gravitational force

• Frictional force

• Strain force

When a force of I newton acts on a mass of kg which is able to move freely, the object moves in the direction of force with a/an:

• speed of 1 km/s

• acceleration of 1 m/s²

• speed of 1 m/s

• acceleration of 1 km/s²

Which one of the following statements is not correct?

• The SI unit of charge is ampere-second

• Debye is the unit of dipole moment

• Resistivity of a wire of length l and area of crosssection a depends upon both l and a

• The kinetic energy of an electron of mass m kg and charge e coulomb, when accelerated through a potential difference of V volt, is eV joule

Two balls, A and B, are thrown simultaneously, A vertically upward with a speed of 20 m/s from the ground and B vertically downward from a height of 40 m with the same speed and along the same line of motion. At what points do the two balls collide by taking acceleration due to gravity as 9.8 m/s²?

• The balls will collide after 3s at a height of 30.2 m from the ground

• 
  The balls will collide after 2s at a height of 20.1 m from the ground

• The balls will collide after ls at a height of 15.1 m from the ground

• The balls will collide after 5s at a height of 20 m from the ground