Question is: An object travels 10 metres in 2 seconds and 10 metres in the next 4 seconds, what is the acceleration. Answer was given -5/6 but I can't work out how they did it. Could you help pls?
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s= ut +½at² (or x = vit + ½at² if you use those symbols)
In the first 2s:
10 = u*2 + ½a*2²
10 = 2u + 2a
u = 5 - a (equation 1)
Over the total of 2+4=6s, displacement = 10+10=20m (assuming both 10m distances are in the positive direction)
20 = u*6 + ½a*6²
20 = 6u + 18a
10 = 3u + 9a
Substituting from equation 1
10 = 3(5-a) + 9a
10 = 15 - 3a + 9a
6a = -5
a= -5/6 m/s² (don't forget units!)
In the first 2s:
10 = u*2 + ½a*2²
10 = 2u + 2a
u = 5 - a (equation 1)
Over the total of 2+4=6s, displacement = 10+10=20m (assuming both 10m distances are in the positive direction)
20 = u*6 + ½a*6²
20 = 6u + 18a
10 = 3u + 9a
Substituting from equation 1
10 = 3(5-a) + 9a
10 = 15 - 3a + 9a
6a = -5
a= -5/6 m/s² (don't forget units!)