Space Exploration Formal Homework 3
Q1. A spacecraft is orbiting the Earth. Scientists prepare to bring it back to the Earth’s
surface.
a) To safely enter the Earth’s atmosphere, the speed of the spacecraft must be
decreased. This is achieved by thruster rockets.
The spacecraft has a mass of 6000 kg and the thruster rockets create a combined
thrust of 4800N.
Calculate the deceleration of the spacecraft when the thruster rockets fire.
(3)
b) The thruster rockets are now switched off. A heat resistant tile breaks off the
spacecraft. The force of gravity near the Earth causes both the spacecraft and the
tile to accelerate towards the Earth.
When the objects enter the Earth’s atmosphere some of the kinetic energy is
transformed into heat.
Name the force that causes this energy transformation.
(1)
Q2. A spacecraft is used to transport astronauts and equipment to a space station. On its
return from space the spacecraft must re-enter the Earth’s atmosphere. The spacecraft has
a heat shield made from special silica tiles to prevent the inside from becoming too hot.
a) Why does the spacecraft increase in temperature when it re-enters the
atmosphere?
(1)
3
b) The mass of the heat shield is 3.5 x 10 kg and the gain in heat energy of the silica
tiles is 4.7 GJ.
Calculate the increase in temperature of the silica tiles.
(3)
c) Explain why the actual temperature rise of the silica tiles is less than the value
calculated in part b).
(1)
d) When a piece of equipment was loaded on to the spacecraft on Earth, two
people were required to lift it. One person was able to lift the same piece of
equipment in the space station.
Explain why one person was able to lift the equipment in the space station. (1)
Q3. An experiment was carried out to determine the specific heat capacity of water. The
energy supplied to the water was measured by a joulemeter.
The following data was recorded.
Initial temperature of the water = 21⁰C.
Final temperature of the water = 33⁰C.
Initial reading on the joulemeter = 12 kJ.
Final reading on the joulemeter = 120 kJ.
Mass of water = 2.0 kg.
Time = 5 minutes.
a) i) Calculate the change in temperature of the water.
(1)
ii) Calculate the energy supplied by the immersion heater.
(1)
iii) Calculate the value for the specific heat capacity of water obtained from this
experiment.
(3)
-1
-1
b) i) The accepted value for the specific heat capacity of water is 4180 J kg ⁰C .
Explain the difference between the accepted value and the value obtained in the
experiment.
(2)
ii) How could the experiment be improved to reduce the difference?
(1)
Q4. 8000kg of pre-heated aluminium pellets at a temperature of 160⁰C are placed in a
container. Aluminium has a specific heat capacity of 902 J kg-1 ⁰C-1 and a melting point of
660 ⁰C.
How much heat energy is required to heat the aluminium to its melting point?
(3)
Q5. A heater is immersed in a
substance. The heater is then
switched on.
The graph shows the temperature
of the substance over a period of
time.
Which row in the table identifies
the sections of the graph when the
substance is changing state?
A
B
C
D
E
Solid to
liquid
QR
QR
PQ
PQ
ST
Liquid to gas
TU
ST
RS
TU
QR
Q6. A solid substance is placed in
an insulated container and is
heated at a constant rate. The
graph shows how the temperature
of the substance changes with
time.
During the time interval QR, which
of the following statements is/are
correct?
I
II
III
A
B
C
D
E
There is a change in the state
of the substance.
The substance changes state
from a liquid to a gas.
Heat is absorbed by the
substance.
I only
III only
I and II only
I and III only
I, II and III