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(a) Calculate the weight of the balloon.
Weight = mass × gravity
W = mg
Where:
- W = weight (in Newtons, N)
- m = mass (120 kg)
- g = gravity (9.81 N/kg)
W = 120 × 9.81
W = 1177.2 N
(b) Show that the acceleration is 0.45 m/s².
Force = mass × acceleration
F = ma
Where:
- F = force (54 N)
- m = mass (120 kg)
a = F ÷ m
a = 54 ÷ 120
a = 0.45 m/s²
(c) Calculate the velocity after 8.0s.
Final velocity = initial velocity + (acceleration × time)
v = u + at
Where:
- u = initial velocity (0 m/s, starts from rest)
- a = acceleration (0.45 m/s²)
- t = time (8.0 seconds)
v = 0 + (0.45 × 8.0)
v = 3.6 m/s
(d) Calculate the distance travelled in 8.0s.
Distance = initial velocity × time + ½ × acceleration × time²
d = ut + ½at²
Where:
- u = initial velocity (0 m/s, starts from rest)
- a = acceleration (0.45 m/s²)
- t = time (8.0 seconds)
d = (0 × 8.0) + ½ × 0.45 × 8.0²
d = 0 + ½ × 0.45 × 64
d = 14.4 m
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(a) (i) Define pressure.
Pressure is how much force pushes on each square meter of a surface.
(ii) Describe how pressure in a liquid varies with its depth and with its density.
With depth:
- The deeper you go, the higher the pressure
- If you double the depth, you double the pressure
With density:
- The heavier the liquid, the higher the pressure
- If you use a heavier liquid, you get more pressure
(b) State two energy sources that don’t come from the Sun.
- Nuclear power (from uranium)
- Geothermal energy (Earth’s heat)
(c) State and explain whether each method of electrical power generation is renewable:
(i) Power generation in a nuclear power station
Non-renewable
Nuclear power stations use uranium fuel which will eventually run out. The fuel cannot be replaced once used up.
(ii) Power generation from waves in the sea
Renewable
Wave power is renewable because waves are constantly created by wind and the moon’s gravitational pull on the oceans. This process continues naturally and won’t run out.
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(a) (i) Which gets bigger most easily when heated: solid, liquid, or gas?
Gets bigger most: Gases
Gets bigger least: Solids
(ii) Describe how tiny bits (particles) behave in solids and gases.
In solids:
- Particles stay in fixed spots
- They just shake a little
- They are packed close together
In gases:
- Particles move everywhere freely
- They are far apart
- They move very fast and bump into each other
Answers – Homework – 1
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