Exercise

Explain why

(a) a heavy truck is fitted with six to fourteen tyres,

(b) skiers use long flat skis to slide over snow,

(c) foundations of high-rise buildings are kept wide.

Why is a person's weight on Jupiter three times more than that on the earth? 

In a horse-cart, each of the two horses pull with a force of $1000 \mathrm{N}$. Find the resultant force. Give reason.

In a game of tug-of-war, three girls of team $A$ pull the rope with the forces of $80 \mathrm{N}$, $100 \mathrm{N}$ and $120 \mathrm{N}$. In the team $B$, three girls pull the rope with the forces of $85 \mathrm{N}$, $105 \mathrm{N}$ and $125 \mathrm{N}$. What is the resultant force? Which team is the winner ? 

A solid object weighs $250 \mathrm{N}$. When placed on a wooden plank, the area of contact is found to be $10 {\mathrm{m}}^2$. Find the pressure exerted by the solid object on the wooden plank.

A brick is $32 \mathrm{cm}$ long, $10 \mathrm{cm}$ wide and $10 \mathrm{cm}$ thick. It weighs $16 \mathrm{N}$ and is lying on the ground. Find the pressure exerted by the brick on the ground. 

A force of $120 \mathrm{N}$ is applied to an object of area $3 {\mathrm{m}}^2$. Calculate the pressure. 

Ramesh's mother emptied a polybag of pulses into a container, some of the pulse grains got stuck to the polythene and did not fall in the container. Give reason