# 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!
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.
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
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
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

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
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).