Question

A small 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 1

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

    $KE = \dfrac{1}{2}mv^2$

    $KE = \dfrac{1}{2}\times 0.2 \times 7.84^2$

    $KE =6.14 J$

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

 $\mu = \dfrac{a}{g}$

 $\mu = \dfrac{3.2}{9.8}$

 $\mu = 0.327$