BTEC L3 Applied Science Unit 5 Physics mid point test

An electrical immersion heater supplies 8.5 kJ of energy every second. Water flows through the heater at a rate of 0.12 kg s^–1 .

Assuming all the energy is transferred to the water, calculate the rise in temperature of the water as it flows through the heater.

specific heat capacity of water = 4200 J kg^–1 K^–1

• 17K

• 215K

• 350K

• 170K

The water suddenly stops flowing at the instant when its average temperature is 26 °C.

The mass of water trapped in the heater is 0.41 kg.

Calculate the time taken for the water to reach 100 °C if the immersion heater continues supplying energy at the same rate.

• 30s

• 1.5s

• 15s

• 180s

A cyclist travelling along a level road at a constant speed of 15 m s^–1 experiences a resistive force of 12 N due to air resistance.

Calculate the power output of the cyclist maintaining this constant speed.

• 18W

• 1.8W

• 180W

• 1800W

The pressure inside a bicycle tyre of volume 1.90 × 10^–3 m³ is 3.20 × 10⁵ Pa when the temperature is 285 K.

Calculate the number of moles of air in the tyre.

• 2.6 mol

• 0.26 mol

• 26 mol

• 260 mol

After the bicycle has been ridden the temperature of the air in the tyre is 295 K.

Calculate the new pressure in the tyre assuming the volume is unchanged.

Give your answer to an appropriate number of significant figures.

• 3.31 × 10⁶ Pa

• 3.31 × 10⁵ Pa

• 0.7 × 10⁵ Pa

• 1.9 × 10⁶ Pa

An ideal gas at a temperature of 22 °C is trapped in a metal cylinder of volume 0.20 m³ at a pressure of 1.6 × 10⁶ Pa.

Calculate the number of moles of gas contained in the cylinder.

• 131

• 13.1

• 13

• 132

The gas has a molar mass of 4.3 × 10^–2 kg mol^–1.

Calculate the density of the gas in the cylinder.

• 2.9

• 23

• 28

• 29

The cylinder is taken to high altitude where the temperature is −50 °C and the pressure is 3.6 × 10⁴ Pa. A valve on the cylinder is opened to allow gas to escape.

Calculate the mass of gas remaining in the cylinder when it reaches equilibrium with its surroundings. Give your answer to an appropriate number of significant figures.

• 0.16

• 0.18

• 0.15

• 0.17

A volume of 0.0016 m³ of air at a pressure of 1.0 × 10⁵ Pa and a temperature of 290 K is trapped in a cylinder. Under these conditions the volume of air occupied by 1.0 mol is 0.024 m³.

The air in the cylinder is heated and at the same time compressed slowly by a piston. The initial condition and final condition of the trapped air are shown in the diagram.

• 0.44

• 0.00044

• 44

• 4.4

Calculate the number of moles of air in the cylinder.

• 0.67

• 0.067

• 6.7

• 67