Physics & Math Practice | Energy - Speed - Heat

H300 Mechanical Engineering

Question:

1. The gas bill for a family shows an energy consumption over the past three months of 485 kW h. Calculate the amount of gas energy consumed by the family over this period. Give your answer in MJ

If each kW h costs 13.86 pence, how much will their bill be at the end of three months? Give your answer in pounds to 2 d.p.

2. In a car crash research facility, tests are carried out on a car carrying crash test dummies and having a total mass of 1.3 tonnes. If the car, carrying the dummies, travels at 27 miles per hour, what is its speed in metres per second (1 d.p.)

Use your final answer (1 d.p.) to calculate the amount of energy absorbed by the end stop, assuming all the kinetic energy is absorbed at that point. Give your answer in kJ to 1 d.p.

3. Given the specific heat capacity of steel is 420 J kg^-1°C^-1,calculate the temperature change when 300 g of steel loses 1550 J of heat. Give your answer to 1 d.p. and include either a +ve or -ve sign in front to indicate the direction of temperature change

4. A 197 g piece of metal is rapidly removed from a furnace at a temperature of 650 °C and quenched in 1700 g of water. The initial temperature of the water is 25 °C.

If the final temperature of both metal and water reach 32 °C and knowing that the specific heat capacity of water is 4190 J kg^-1 °C^-1, calculate the specific heat capacity of the metal in J kg^-1 °C^-1, (to 1 d.p.).

5. A steam iron carries a current of 14 A when connected to a 240 V source.

What is the resistance of the steam iron? Give your answer to 2 significant figures.

6. resistors of 3 Ω and 9 Ω are connected, in series, to a 52 V power source.

Calculate the current through the circuit in mA and to 4 significant figures

7. A quantity of concrete has to be mixed using a ratio of 1:3:6 cement:sand:gravel.

What quantity of gravel will be needed (in m³) if the total quantity required is 2.90 m³?

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