Question 6 (12 marks) Use a SEPARATE writing booklet - HSC - SSCE Mathematics Extension 1 - Question 6 - 2002 - Paper 1
Question 6
Question 6 (12 marks) Use a SEPARATE writing booklet.
(a)
An angler casts a fishing line so that the sinker is projected with a speed V m s\text{-1} from a point 5 ... show full transcript
Worked Solution & Example Answer:Question 6 (12 marks) Use a SEPARATE writing booklet - HSC - SSCE Mathematics Extension 1 - Question 6 - 2002 - Paper 1
Step 1
i) Let (x,y) be the position of the sinker at time t seconds after the cast, and before the sinker hits the water.
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Answer
The horizontal motion is given by the equation for displacement:
x=Vtcosθ
To express y in terms of x, we can use the equations of motion. The vertical displacement from launch to the position just before it hits the water is derived from:
y=Vtsinθ−21gt2
With g being the acceleration due to gravity (10 m/s²), this simplifies to:
y=Vtsinθ−5t2+5.
This shows the relationship between the vertical position y and the parameters given.
Step 2
ii) Suppose the sinker hits the sea 60 metres away as shown in the diagram.
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Answer
Using the horizontal motion equation:
x=60=Vtcosθ
Substituting \theta = \tan^{-1}\left(\frac{3}{4}\right)$, gives us:
Vt=cos(θ)60
Now we find \sin(\theta) using:
tan(θ)=43⇒sin(θ)=53,cos(θ)=54
Therefore,
t=V⋅5460=V75
Now, substituting (t) back into the vertical motion equation, we can find the value of V algebraically.
Step 3
iii) For the cast described in part (ii), find the maximum height above sea level that the sinker achieved.
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Answer
To find the maximum height, we set the vertical velocity to zero:
0=Vsinθ−gt
Solving for t at maximum height,
t=gVsinθ
Substituting back into the y-position function:
ymax=Vtsinθ−5t2+5
We will find our maximum height using this t value and substituting the corresponding V and sin(θ) values.