# Projectiles question help

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#1
I am struggling to work out part b for this question:

A particle is projected horizontally at 40ms^-1 from a point P, which is h metres above a horizontal plane. The particle hits the plane a horizontal distance of 100m from P. Work out:

a) the time taken for the particle to land (i worked out it was 2.5s)

b) the value of h
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1 month ago
#2
(Original post by lovescience2002)
I am struggling to work out part b for this question:

A particle is projected horizontally at 40ms^-1 from a point P, which is h metres above a horizontal plane. The particle hits the plane a horizontal distance of 100m from P. Work out:

a) the time taken for the particle to land (i worked out it was 2.5s)

b) the value of h
It's a suvat question, where you consider the horizontal and vertical motion seperately. What have you tried?
Last edited by mqb2766; 1 month ago
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#3
(Original post by mqb2766)
It's a suvat question, where you consider the horizontal and vertical motion seperately. What have you tried?
I tried doing s=ut + 1/2at^2 using s=? u=40 a= 9.8 t=0 which would give an answer of 0, but that is incorrect
0
1 month ago
#4
(Original post by lovescience2002)
I tried doing s=ut + 1/2at^2 using s=? u=40 a= 9.8 t=0 which would give an answer of 0, but that is incorrect
Yes, the u=40 is the horizontal velocity and g=-9.8 is the vertical acceleration. They must be considered in separate suvat equations. You can't combine them like that. Also t is generally the time to cover a displacement s, not 0.
Draw a diagram, and think about the horizontal motion for the first part. Which suvat terms do you know and which do you need to calculate?
Last edited by mqb2766; 1 month ago
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