diet and nutrients
what is a balanced diet
eating the right types and amounts of foods to give your body the energy and nutrients it needs to work well
What is the tiny particle that makes up all matter and contains a nucleus?
atoms
What is a force?
a push or a pull of an object
What is a renewable energy source?
An energy source that is naturally replaced at about the same rate it is used.
What is pressure, and what is its SI unit?
Pressure is the force acting per unit area. Its SI unit is the pascal
name 2 nutrients that provide energy to the body
carbohydrates and fats
Name the three main subatomic particles.
Protons, neutrons and electrons
What is the unit used to measure force?
Newtons(N)
Give two examples of renewable energy sources.
hydro power, solar power, wind power etc
A force of 120 N acts on an area of 6 m². Calculate the pressure.
20 Pa
why is fibre important in our diet
prevents constipation
Which subatomic particle has a negative charge?
electrons
What happens to the motion of an object when the forces acting on it are balanced?
it remains stationery
Is coal renewable or non-renewable? Explain why.
non-renewable as it takes millions of years to replenish
Explain why a drawing pin has a sharp point but a wide flat head. Your answer should relate to pressure.
The sharp point has a small area, so the force produces a large pressure, allowing it to penetrate the material. The wide head spreads the force over a larger area, producing less pressure on the person's finger.
A child has weak bones and teeth because their diet lacks an important mineral. What mineral is likely missing, and why is it needed
Calcium — it is needed for strong bones and teeth.
An atom has 11 protons, 11 electrons and 12 neutrons. What is its atomic number and mass number?
Atomic number = 11; Mass number = 23
A car travels 150 metres in 10 seconds. What is its average speed?
15 M/s
Give one advantage and one disadvantage of using solar energy.
advantage: renewable
disadvantges: expensive or not viable in placess without sunlight
A perfume bottle is opened in one corner of a room. At first, the perfume particles are highly concentrated near the bottle.
Explain how diffusion causes the smell to spread through the room, and explain what happens to the rate of diffusion as the concentration difference decreases.
Perfume particles move randomly from the region of higher concentration to regions of lower concentration. As the particles spread out, the concentration difference becomes smaller, so the net rate of diffusion decreases. Eventually the particles become evenly distributed, although they continue moving randomly.
Explain why a growing teenager generally needs a balanced diet containing protein, carbohydrates, fats, vitamins, minerals, fibre and water.
A growing teenager needs a balanced diet because the body needs different nutrients for energy, growth, repair, healthy bones, normal body functions, and digestion.
Explain why an atom normally has no overall electrical charge, even though it contains charged particles
An atom normally has equal numbers of protons and electrons. Their positive and negative charges cancel each other out, giving the atom no overall charge.
A cyclist is moving forwards. The driving force is 400 N, while air resistance and friction together provide 250 N backwards. What is the resultant force, and what will happen to the cyclist's motion?
Resultant force = 150 N forwards. The cyclist will accelerate forward
Compare renewable and non-renewable energy sources. Include how quickly they are replaced, their environmental impact, and examples of each
Renewable sources are naturally replenished, such as solar and wind, and generally produce less greenhouse-gas pollution. Non-renewable sources, such as coal, oil and natural gas, are finite and generally produce more pollution when burned.
A student investigates diffusion using two identical containers of water. One contains water at 20°C, while the other contains water at 60°C. The same amount of dye is added to each.
Predict which container will become evenly coloured first and explain, using particle movement and temperature, why this happens. Then explain why the dye eventually becomes evenly distributed rather than remaining concentrated in one region.
The 60°C container becomes evenly coloured first. At a higher temperature, particles have more kinetic energy and move around faster, so diffusion occurs more quickly.
The dye spreads from an area of higher concentration to lower concentration because of the random movement of particles. As the dye becomes more evenly distributed, the concentration difference decreases. Eventually there is no net movement in one direction, even though the particles continue moving randomly.