# Zone d’entraide

### Question de l’élève

Secondaire 5 • 3a

Concerned with safeguarding the environment, Serge hunts with and arrow. He stands on a platform in a tree, 6.0m above the ground. One day, after Serge stood waiting motionless for 2 hours, a rabbit appeared, 12.0m from the foot of the tree. Trembling with impatience, Serge drew his bow, leaned forward and shot and arrow with an initial velocity of 60.0 m/s and an angle of depression of 30.0 degrees. Did the arrow hit the target?

What formula do we use to solve this situation?

1st step: What formula to find the components of the initial velocity? For the horizontal and vertical components ?

2nd step: what is the equations for the arrow's horizontal position and vertical position ?

3rd step: what is the formula for the time of flight?

and then with those information what is next to solve the problem?

and if possible when giving the formulas can you mention what the variables are

Thank you

Physique

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## Explications (1)

• Explication d'Alloprof

Explication d'Alloprof

Cette explication a été donnée par un membre de l'équipe d'Alloprof.

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Équipe Alloprof • 3a

Hi Brit,

Thanks for your question!😉

1- You could try to use the angle of depression and find the corresponding vector of the speed. You'll need to use trigonometry to find the components as you already have the magnitude (60.0 m/s) and the angle (30.0 degrees) of the vector.

2- I can refer you to our physics equations, they will be in french, but I can translate the variables so that you understand them.

Vmoy : Average speed Δx : difference in distance Δt : time a : acceleration Δv : difference in speed vf : final speed vi : initial speed

For this question you need to use one of these formulas to find the equations between the time and the position (x and y) of the arrow. You'll also need the speed that you found earlier.

3- Again, these formulas will be useful along with the speed and height/distance.

I hope that it is clear enough and that you are able to start your problem with my explanations!

If you have other questions, feel free to ask them!😉

Anthony B.

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