# Mechanics Help!

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#1
Stuck on this question, it’s 6 marks!

“A constant force of F N acts on a particle of mass 5 kg for 4 seconds.

The particle’s initial speed was 2i+5j ; its final speed is 18i−3j.

Find the magnitude of F”

Some help would be much appreciated!
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1 week ago
#2
(Original post by Hallowkin)
Stuck on this question, it’s 6 marks!

“A constant force of F N acts on a particle of mass 5 kg for 4 seconds.

The particle’s initial speed was 2i+5j ; its final speed is 18i−3j.

Find the magnitude of F”

Some help would be much appreciated!
find acceleration first : v - u /t = a and you get 16 i - 8 j / 4 = 4 i - 2 j
using F = ma , u get 5 x (4i - 2j) = 20 i - 10j
magnitude of this is the square root of 20^2 + (-10)^2 = 10 root 3 which approximates to 17. 32 N to 4sf
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