Question.

Calculate the mass of nitrogen (IV) oxide gas that would occupy the same volume as 10g of hydrogen gas at the same temperature and pressure. (H = 1.0, N = 14.0, O = 16.0)

Answer.

For Hydrogen, H2, molar mass= 2g

2g= 1mole
10g =?

(10g x 1 mole)/2g= 5moles of hydrogen gas.

For Nitrogen (IV) oxide gas, NO2

Molar mass = 14 + 32 = 46g

1 mole of NO2= 46g
5 moles of NO2 =?

(5moles x 46g)/1mole= 230g of NO2 gas will occupy the same volume of 10g of H2 gas

 (I) What type of energy does it have?

 (ii) When the brakes are applied, the car is brought to a stop. What has happened to the energy it had whilst moving?

 (b) The car starts going up a hill. The driver notices that the speed of the car begins to decrease. He has not applied the brakes or altered the setting on the accelerator. Explain in terms of energy why the car’s speed begins to decrease.

 (c) When the driver brakes, the distance needed to stop the car moving at 30 m/s up a hill is less than the distance on a flat road. Explain why.

(d) A journey involving a lot of speeding up and slowing down uses more petrol than one where the speed remains fairly constant. Explain this in terms of energy.

Question.

(a) A car is travelling along a straight flat road at 30 m/s.

 (I) What type of energy does it have?

 (ii) When the brakes are applied, the car is brought to a stop. What has happened to the energy it     had whilst moving?

 (b) The car starts going up a hill. The driver notices that the speed of the car begins to decrease. He has not applied the brakes or altered the setting on the accelerator. Explain in terms of energy why the car’s speed begins to decrease.

 (c) When the driver brakes, the distance needed to stop the car moving at 30 m/s up a hill is less than the distance on a flat road. Explain why.

(d) A journey involving a lot of speeding up and slowing down uses more petrol than one where the speed remains fairly constant. Explain this in terms of energy.

Answer.

a) (i) Kinetic energy.

(ii) The energy is transferred to heat or thermal energy.

b) The kinetic energy of the car is transferred to potential energy as the car go up the hill.

c) less work has to be done by the brakes as some energy transferred to
gravitational potential energy.

d) when stopping kinetic energy transferred to heat and it is lost to the atmosphere when braking and also more fuel burnt when speeding up.