A snooker ball of mass $0.4 \mathrm{kg}$ is struck towards a cushion from $0.8 \mathrm{m}$ away with speed $3 \mathrm{m}{\mathrm{s}}^{-1}.$ The surface of the snooker table has a coefficient of friction of $0.3.$ When the ball bounces from the cushion its speed is reduced by $20\%.$ Find how far from the cushion it stops.

A wooden block of mass $10 \mathrm{kg}$ is on rough horizontal ground with coefficient of friction $0.6.$ It is dragged by a force of $80 \mathrm{N}$ acting at $15°$ to the horizontal.

Find the acceleration if the force is above the horizontal.

A wooden block of mass $10 \mathrm{kg}$ is on rough horizontal ground with coefficient of friction $0.6.$ It is dragged by a force of $80 \mathrm{N}$ acting at $15°$ to the horizontal.

Find the acceleration if the force is below the horizontal.

A box of mass $50 \mathrm{kg}$ is slowing down from $10 \mathrm{m}{\mathrm{s}}^{-1}$ on rough horizontal ground. The coefficient of friction between the box and the ground is $0.3.$ To start with, the box is being slowed by a string providing a tension of $25 \mathrm{N}$ horizontally. Then the string breaks and the box comes to a halt under friction alone after a total distance of $14.5 \mathrm{m}.$

Find how far the box travelled before the string broke.

A box of mass $50 \mathrm{kg}$ is slowing down from $10 \mathrm{m}{\mathrm{s}}^{-1}$ on rough horizontal ground. The coefficient of friction between the box and the ground is $0.3.$ To start with, the box is being slowed by a string providing a tension of $25 \mathrm{N}$ horizontally. Then the string breaks and the box comes to a halt under friction alone after a total distance of $14.5 \mathrm{m}.$

What assumptions have been made to answer the question?

A book of mass $3 \mathrm{kg}$ is at rest on a rough slope at an angle of $15°$ to the horizontal. It takes a force of $20 \mathrm{N}$ parallel to the slope to break equilibrium and drag it up the slope.

Find the coefficient of friction between the slope and the book.

A book of mass $3 \mathrm{kg}$ is at rest on a rough slope at an angle of $15°$ to the horizontal. It takes a force of $20 \mathrm{N}$ parallel to the slope to break equilibrium and drag it up the slope.

Find the acceleration of the book down the slope if the $20 \mathrm{N}$ force is applied down the slope.

A box of mass $12 \mathrm{kg}$ is at rest on a rough slope at an angle of $18°$ to the horizontal. The coefficient of friction between the slope and the box is $0.4.$

Find the force it takes parallel to the upwards slope to break equilibrium and drag the box up the slope.