2005 HSC Question 19. (1 Viewer)

Divinity_ · Oct 12, 2009

the-derivative · Oct 12, 2009

The above statement made by Lovell is true. This is because the path of the spacecraft will be dependent on the gravitational forces and theories of gravitational forces were formed by Isaac Newton. (i.e. F = GMM/d^2)

Also the path of the rockets will abide by Newton's laws - i.e. the rocket will remain in constant motion and that the acceleration of the rocket will be dependent on the force (newton's 1st and 2nd laws).

Therefore, because the rocket launch and trajectory of its return was dependent on the gravitational forces, Lovell's statement can be considered true as it was through the ideas of Newton which allowed for a successful mission.

helper · Oct 12, 2009

1 for derivative

To return safely to Earth, the spacecraft from the time of stopping the engine, needs to continue in a spiralling path to the landing site and reduce its velocity.

Gravity is applying a force towards the centre of the Earth, that enables the spacecraft to continue its path around the Earth and is attempting to accelerate towards the centre of the Earth. (given by Newton's Law of universal gravitation)

As the spacecraft is changing direction and slowing down, it is experiencing a net force, as stated by Newton's firsts law, that an object will remain in its same state of motion, unless acted on by a net external force.

Newton's 2nd Law was used to determine the magnitude of the acceleration (F=ma) and if that law doesn't hold the spacecraft will not reduce its acceleration enough to land in the correct position of will not have a succesful reentry.

On landing the spacecraft will hit the ground and the ground will exert an equal force back on the spacecraft (Newton's 3rd Law). If this force is too large, then the astronauts will experience too high a g-force and could be injured on landing.

So the statement is justified because if the astronauts hadn't correctly applied the 4 laws from Newtown, the spacecraft couldn't land succesfully. They only had the calculations based on his laws to control the spacecraft back to ground.

This isn't an exemplar answer but is the type of thing they were after. Each law is stated in a relevent part of the answer and goes through the reason it justifies his statement. This was a very poorly done question.

imoO · Oct 12, 2009

the-derivative said:
The above statement made by Lovell is true. This is because the path of the spacecraft will be dependent on the gravitational forces and theories of gravitational forces were formed by Isaac Newton. (i.e. F = GMM/d^2)

Also the path of the rockets will abide by Newton's laws - i.e. the rocket will remain in constant motion and that the acceleration of the rocket will be dependent on the force (newton's 1st and 2nd laws).

Therefore, because the rocket launch and trajectory of its return was dependent on the gravitational forces, Lovell's statement can be considered true as it was through the ideas of Newton which allowed for a successful mission.

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Newton's first law - the law of inertia, an object will continue what it was originally doing unless acted upon by an external force
in this case, the rocket will continue accelerating, because it is being acted upon by the gravitational field of the moon

Newton's second law - a body that experiences a force will experience an acceleration (F=ma)
because there is a force provided by the rocket engines(when they are turned on), the rocket will experience an acceleration. when the rocket engines are turned on, the rocket will experience acceleration to move out of the gravitational field

Newton's third law - for every force, there is an equal and opposite force
although the force generated by the rocket engines are opposed by g-forces, they g-forces are relatively smaller, thus the rocket's ability to accelerate out of the gravitational field.

the-derivative · Oct 12, 2009

helper said:
1 for derivative

To return safely to Earth, the spacecraft from the time of stopping the engine, needs to continue in a spiralling path to the landing site and reduce its velocity.

Gravity is applying a force towards the centre of the Earth, that enables the spacecraft to continue its path around the Earth and is attempting to accelerate towards the centre of the Earth. (given by Newton's Law of universal gravitation)

As the spacecraft is changing direction and slowing down, it is experiencing a net force, as stated by Newton's firsts law, that an object will remain in its same state of motion, unless acted on by a net external force.

Newton's 2nd Law was used to determine the magnitude of the acceleration (F=ma) and if that law doesn't hold the spacecraft will not reduce its acceleration enough to land in the correct position of will not have a succesful reentry.

On landing the spacecraft will hit the ground and the ground will exert an equal force back on the spacecraft (Newton's 3rd Law). If this force is too large, then the astronauts will experience too high a g-force and could be injured on landing.

So the statement is justified because if the astronauts hadn't correctly applied the 4 laws from Newtown, the spacecraft couldn't land succesfully. They only had the calculations based on his laws to control the spacecraft back to ground.

This isn't an exemplar answer but is the type of thing they were after. Each law is stated in a relevent part of the answer and goes through the reason it justifies his statement. This was a very poorly done question.

Yep, I know that, but I wouldn't have written something that brief in an exam. I was just giving an overview of how the OP would approach the question.

helper · Oct 13, 2009

imoO said:
the-derivative is correct, but you can also chuck in the third newton law, just to be safe. im thinking 1 mark for assessing the statement, and 1 mark for each law.

Newton's first law - the law of inertia, an object will continue what it was originally doing unless acted upon by an external force
in this case, the rocket will continue accelerating, because it is being acted upon by the gravitational field of the moon

Newton's second law - a body that experiences a force will experience an acceleration (F=ma)
because there is a force provided by the rocket engines(when they are turned on), the rocket will experience an acceleration. when the rocket engines are turned on, the rocket will experience acceleration to move out of the gravitational field

Newton's third law - for every force, there is an equal and opposite force
although the force generated by the rocket engines are opposed by g-forces, they g-forces are relatively smaller, thus the rocket's ability to accelerate out of the gravitational field.

Your answer is a lot better but still only 2 because:
1. It has stated the laws. Derivative implied them but didn't state them and the way the 1st and 2nd are listed was contradictory (2 marks)

However
Statement 1 is incorrect because it is before the statement, so wouldn't have boosted you above 2

Statement 2 is about before the statement, so is irrelevant for the same reason

Same with statement 3, because no rockets used in landing.

Marking Scheme

4 Marks
Presents a logical, coherent argument to support Jim Lovell’s statement,
for the period after the rocket burn including correct, relevant description
of Newton’s laws

3 Marks
• Describes and explains the relevance of Newton’s laws to the solution of
the astronaut’s problem for the period after the rocket burn

2 Marks
• Correctly identifies and relates one of Newton’s laws to the situation for
the periods either before or after the rocket burn
OR
• States two of Newton’s laws

1 Mark
• Correctly states one of Newton’s laws 1

2005 HSC Question 19. (1 Viewer)

Divinity_

Member

the-derivative

BCom/LLB (UNSW)

helper

Active Member

imoO

Member

the-derivative

BCom/LLB (UNSW)

helper

Active Member

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