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Projectiles Question

https://www.quora.com/profile/Bravewarrior/p-169741938
Here is the question with its solution. I'm stuck on parts b and c. Some help would be greatly appreciated!

Reply 1

Original post by pigeonwarrior
https://www.quora.com/profile/Bravewarrior/p-169741938
Here is the question with its solution. I'm stuck on parts b and c. Some help would be greatly appreciated!

What have you tried? Post your working - it's never sensible to look at the answer too quickly btw.

Reply 2

Original post by Muttley79
What have you tried? Post your working - it's never sensible to look at the answer too quickly btw.

I've only managed to do part a😭.
For b and c, I think I'm a bit confused as to what the question is even asking me to do, and that is why I don't understand the markscheme

Reply 3

Original post by pigeonwarrior
I've only managed to do part a😭.
For b and c, I think I'm a bit confused as to what the question is even asking me to do, and that is why I don't understand the markscheme

As Muttley says, perhaps put aside the mark scheme and think about the maths / physics for a bit...

For part (b) you are given the initial velocity, which has a horizontal (i-) component and a vertical (j-) component. As the ball moves from O to A, which component(s) vary. Does one or both of the components have a minimum value during the motion? How does speed depend on the two components?

You should be able to write down the answer - hence only 1 mark :smile:

Reply 4

Original post by davros
As Muttley says, perhaps put aside the mark scheme and think about the maths / physics for a bit...
For part (b) you are given the initial velocity, which has a horizontal (i-) component and a vertical (j-) component. As the ball moves from O to A, which component(s) vary. Does one or both of the components have a minimum value during the motion? How does speed depend on the two components?
You should be able to write down the answer - hence only 1 mark :smile:

ohh yes the horizontal component is the one that stays the same throughout the journey hence 9 🫢
for part c, I don't understand what equation they've used, I thought I could just use suvat after working out the vertical component of the velocity

Reply 5

Original post by pigeonwarrior
ohh yes the horizontal component is the one that stays the same throughout the journey hence 9 🫢
for part c, I don't understand what equation they've used, I thought I could just use suvat after working out the vertical component of the velocity
You can (and that's what they've done: found the start and end vertical velocities for which the total speed is < 12 m/s, then solve for time given acceleration).

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