When salt is spread on a road during winter, corrosion of motor cars is a major problem Justify .

The soldiers of Napolean army while at Alps during freezing winter suffered a serious problem as regards to the tin buttons of their uniforms. White metallic tin buttons get converted to grey powder, This transformation is related to

When a car of 3mass 1000 kg is moving with a velocity of 20ms^(-1) on a rough horizontal road, its engine is switched off. How far does the car move before it comes to rest if the coefficient of kinetic friction between the road and tyres of the car is 0.75 ?

When a car of mass 1200 kg is moving with a velocity of 15 ms^(-1) on a rough horizontal road, its engine is switched off. How far does the car travel before it comes to rest if the coefficient of kinetic friction between the road and tyres of the car is 0.5? ( g=10ms^(-2) )

When we go on a busy road in the evening a lot of smoke is spread in the surroundings. We get cough and feel uneasy even when we close the nose with napkins. Why this type of symptoms we observe? Think about it. If these symptoms will continue, what happens?