Teacher's notes and answers to questions in the book - Hodder Plus ...

WJEC GCSE Additional Science Teacher’s Notes
p = mv = 400 000 × 7700 = 3 080 000 000 kg m/s
5. At take-off, the Space Shuttle leaves the launch tower travelling at 45 m/s. The momentum of the
Shuttle at this point is 90 000 000 kg m/s. What is the mass of the Shuttle at this point Why isn’t the
mass of the Shuttle constant
p 90 000 000
p = mv m 2 000 000 kg
v 45
As fuel is used up, the mass goes down.
6. When the solid rocket boosters and the external fuel tank are jettisoned, the Space Shuttle has a
momentum of 140 000 000 kg m/s, and a mass of 100 700 kg. What is the velocity of the Shuttle at this
point
p = mv
p 140 000 000
v
1390
m/s
m 100 700
7. Use the mass and momentum information in these questions and the rest of the text to describe how
the mass, velocity and momentum of the Shuttle change during its flight up to docking with the ISS.
What is the final momentum of the Shuttle just before docking with the ISS
On launch pad before engine on: mass constant, velocity zero, momentum zero
At moment of take-off: mass decreasing, velocity increasing, momentum increasing
Up to jettison of tanks: mass decreasing, velocity increasing, momentum increasing
Orbit just before docking (engines off): mass constant, velocity constant, momentum
constant
_The forces and motion at take-off (pages 181–84)____
Discussion point
A Space Shuttle (mass = 78 000 kg) docks with the ISS (mass = 385 471 kg). At the moment of docking the
ISS is effectively stationary and the Space Shuttle is moving at 2 m/s relative to the ISS. What are the
relative momentums of the Space Shuttle and the ISS before docking, and what is their combined
momentum after docking What is the effective increase in speed of the ISS What does this tell you about
momentum and collisions
Relative momentum of Space Shuttle = mv = 78 000 × 2 = 156 000 kg m/s
Relative momentum of ISS = 0 kg m/s
Combined relative momentum after docking = 156 000 kg m/s
p 156 000
p = mv v
0.34 m/s
m (78 000 385 471)
Momentum is conserved during collisions.
PRACTICAL Investigating Newton’s second law
(pages 182–83)
This experimental demonstration works best using data-logging software that calculates
acceleration directly. Remember to pre-load the glider with weights that can be transferred to
the mass stack so that the total accelerating mass remains constant.
1. Calculate values of force/acceleration in your table and record them.
Calculated values will depend upon data obtained.
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