Asmall block of mass 200 g starts at rest at a, slides to b where its speed is vb=8.0m/s, vb=8.0m/s, then slides along the horizontal surface a distance 10 m before coming to rest at c. (see below.) (a) what is the work of friction along the curved surface? (b) what is the coefficient of kinetic friction along the horizontal surface?

Answer

given,

mass of the block = 200 g = 0.2 Kg

Velocity at A = 0 m/s

Velocity at B = 8 m/s

slide to the horizontal distance = 10 m

height of the block be = 4 m

potential energy of the block

    P = m g h

    P = 0.2 x 9.8 x 4

    P =7.84 J

kinetic energy

Work = P - KE

work = 7.84 - 6.14

work = 1.7 J

b) v² = u² + 2 a s

   0 = 8² - 2 x a x 10

   a = 3.2 m/s²

ma - μ mg = 0

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.