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Two balls of mass 3kg and 7 kg respectively move towards one another with speeds 5ms^-1 and 2ms^-1 respectively on a smooth table. If they collide and join, what velocity do they move off with?

m = 3kg ; 7kg u = 5ms^-1 ; -2ms^-1 (Taking the direction to the right as positive). momentum before = m1u1 + m2u2 = (3x5) + (7x-2) = 1 momentum after = (m1+m2)v2 = (3+7)v = 10v By the principle of conserv...

Answered by Aimee G. • Physics tutor

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Find the angle at which total internal refraction takes place when light is going from glass to air.

The angle at which this takes place is called the critical angle.

We can apply Snell's law in this situation: n₁sin C1 = n₂sin (90deg)

sin C = n₂/ n

Answered by Catherine T. • Physics tutor

1876 Views

Why can heat only be transferred through a vacuum by radiation, and not conduction or convection? (3)

Heat transfer by conduction and convection works by particles colliding and transferring energy, as there are no particles in a vacuum heat transfer can only occur by radiation. This is because radiati...

Answered by James W. • Physics tutor

36025 Views

Explain the photoelectric effect, when does it occur and what is its significance in understanding the nature of light ? (6)

metal (unlike insulators ) contains free electrons (1)

kinetic energy transferred from the light incident on the surface to the free electrons (1)

The maximum kinetic energy of the electrons...

Answered by Helena R. • Physics tutor

1912 Views

The mercury atoms in a fluorescent tube are excited and then emit photons in the ultraviolet region of the elecrtomagnetic spectrum. Explain how the mercury atoms become excited.

The mercury atom is excited one of its electrons goes from an upper electron shell to a lower electron shell thanks to some energy that it recives from the outside. When an atom is excited it is instable ...

Answered by Marie B. • Physics tutor

4774 Views