Jan Dangerfield, Stuart Haring and, Julian Gilbey Solutions for Exercise 5: EXERCISE 2D

An elevator is carrying a child of mass $40 \mathrm{kg}$ downwards. It is travelling at $8 \mathrm{m}{ \mathrm{s}}^{-1}$ and starts to slow down at constant acceleration when it is $6.25 \mathrm{m}$ from where it stops. Find the size of the normal contact force on the child.

A forklift truck carries a wooden pallet. On the pallet is a box of tiles with mass $35 \mathrm{kg}.$ The truck lifts the pallet and tiles with an initial acceleration of $2 \mathrm{m}{ \mathrm{s}}^{-2}.$ Find the normal contact force on the tiles.

A weightlifter is trying to lift a bar with mass $200 \mathrm{kg}$ from the floor. He lifts with a force of $1800 \mathrm{N}$ but cannot lift it off the floor. Find the size of the normal contact force from the floor on the bar while the weightlifter is trying to lift the bar.

A plate of mass $0.7 \mathrm{kg}$ is being held on a horizontal tray. The tray is lifted from rest on the floor and accelerates at a constant rate until it reaches a height of $1.25 \mathrm{m}$ after $5 \mathrm{s}.$ Find the normal contact force on the plate.

A man of mass $75 \mathrm{kg}$ is standing in the basket of a hot-air balloon. The balloon is rising at $5 \mathrm{m}{ \mathrm{s}}^{-1}$ and $4 \mathrm{s}$ later it is descending at $3{ \mathrm{ms}}^{-1}.$ Assuming constant acceleration, find the normal contact force on the man.

A girl of mass $45 \mathrm{kg}$ is sitting in a helicopter. The helicopter rises vertically with constant acceleration from rest to a speed of $40 \mathrm{m}{ \mathrm{s}}^{-1}$ when it reaches a height of $200 \mathrm{m}.$

Find the normal contact force on the girl.

A girl of mass $45 \mathrm{kg}$ is sitting in a helicopter. The helicopter rises vertically with constant acceleration from rest to a speed of $40 \mathrm{m}{ \mathrm{s}}^{-1}$ when it reaches a height of $200 \mathrm{m}.$

What assumptions have been made to answer the question?

A drone carries a parcel of mass $4 \mathrm{kg}.$ The parcel is held in place by two pads, on its top and on its bottom. The drone hovers at a height of $30 \mathrm{m}$ before descending for $2 \mathrm{s}$ to a height of $8 \mathrm{m}.$ Find the normal contact force acting on the parcel as it descends and determine whether the force acts from the top pad or the bottom pad.