A country needs a new power station. It could build a hydroelectric power station in a mountain valley or a gas-fired power station near a town.
Comparison of two power stations. Hydroelectric: fuel cost none; carbon dioxide when generating none; start-up time about 1 minute; building cost very high; needs a flooded valley. Gas-fired: fuel cost high; carbon dioxide when generating yes; start-up time about 15 minutes; building cost medium; can be built near towns.
Feature
Hydroelectric
Gas-fired
Fuel cost
None
High
Carbon dioxide when generating
None
Yes
Start-up time
About 1 minute
About 15 minutes
Building cost
Very high
Medium
Site
Needs a flooded valley
Can be built near towns
Evaluate the two options. Use information from the table and your own knowledge.
[6 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Radium-226 decays by emitting an alpha particle:
88226Ra→ZARn+24He
.1
Determine the mass number A of the radon nucleus.
[1 mark]
.2
Determine the atomic number Z of the radon nucleus.
[1 mark]
.3
Strontium-90 decays by beta emission. Describe what happens in the nucleus during beta decay.
[2 marks]
7 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A skydiver of mass 75 kg jumps from a plane.
Gravitational field strength = 9.8 N/kg.
.1
At one moment the air resistance on the skydiver is 285 N. Calculate the acceleration of the skydiver at this moment.
[3 marks]
.2
Explain why the skydiver reaches a terminal velocity.
[4 marks]
4 marksFoundation
Spec and skills
Original practice question
Answer and supported method checks
An electric kettle has an input power of 2000 W. The useful power output, heating the water, is 1800 W.
.1
Calculate the efficiency of the kettle.
[2 marks]
.2
Calculate the power wasted by the kettle.
[1 mark]
.3
Give one way energy is wasted by the kettle.
[1 mark]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A tired driver is driving fast on a wet road at night.
Explain how each of these factors affects the stopping distance of the car.
