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# HELP M1 Again watch

1. A particle is moving along the x-axis with constant deceleration 5ms-2. At time=0, the particle passes through the origin o with velocity 12ms-1 in the positive direction. At time t secounds the particle passes through the point A with x-coordinates 8. Find the values of t.

Any help?

I know the formula that is used is s=ut+1/2at^2 but I keep getting the wrong answer.
2. (Original post by Mist786)
A particle is moving along the x-axis with constant deceleration 5ms-2. At time=0, the particle passes through the origin o with velocity 12ms-1 in the positive direction. At time t secounds the particle passes through the point A with x-coordinates 8. Find the values of t.

Any help?

I know the formula that is used is s=ut+1/2at^2 but I keep getting the wrong answer.
a=-5
3. (Original post by rbnphlp)
a=-5
I still get the wrong answer.I sustituted the values
4. u=12
a= -5
s=8
t= ?
s= ut + 1/2 at^2
8= 12t -2.5t^2
5t^2-24t+16=0
(5t-4)(t-4)=0
t=4, t=0.8
5. (Original post by Revolution is my Name)
u=12
a= -5
s=8
t= ?
s= ut + 1/2 at^2
8= 12t -2.5t^2
5t^2-24t+16=0
(5t-4)(t-4)=0
t=4, t=0.8
Thanks
btw, cool profile
6. (Original post by Mist786)
A particle is moving along the x-axis with constant deceleration 5ms-2. At time=0, the particle passes through the origin o with velocity 12ms-1 in the positive direction. At time t secounds the particle passes through the point A with x-coordinates 8. Find the values of t.

Any help?

I know the formula that is used is s=ut+1/2at^2 but I keep getting the wrong answer.
a= -5ms-2
u = 12ms-1
s = 8

Sub in the values and rearrange into a quadratic and solve
7. How'd you solve it if the next question was: Find the velocity of the particle as it passes through the point with x-coordinate -8
8. (Original post by Mist786)
How'd you solve it if the next question was: Find the velocity of the particle as it passes through the point with x-coordinate -8
Sub in s=-8 instead and see what happens?
9. (Original post by Revolution is my Name)
Sub in s=-8 instead and see what happens?
I get the wrong answer because the question asks what is the velocity not time
10. (Original post by Mist786)
I get the wrong answer because the question asks what is the velocity not time
Well, you've got u=0, s=-8, a=-5, and are trying to find v; do you know an equation of motion linking those four?
11. You may be expected to use more than one SUVAT equation in one question if it's long, so don't confine yourself to just the s=ut+1/2at^2.
12. (Original post by Revolution is my Name)
Well, you've got u=0, s=-8, a=-5, and are trying to find v; do you know an equation of motion linking those four?
If I use the formula v^2=2as-u^2, I stll get the wrong answer when I substitute usa in the formula. How is u=0?
13. (Original post by Mist786)
If I use the formula v^2=2as-u^2, I stll get the wrong answer when I substitute usa in the formula. How is u=0?
Ah sorry, u=12; I'm a bit too used to doing these starting from rest.
I'm pretty sure the equation is actually v^2=u^2+2as; try it with that and see if that gives you the right answer.
14. (Original post by Revolution is my Name)
Ah sorry, u=12; I'm a bit too used to doing these starting from rest.
I'm pretty sure the equation is actually v^2=u^2+2as; try it with that and see if that gives you the right answer.
Okay, cool

Thanks

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