A level Maths help mechanics

First, try using F=ma to create equations of motion for the trailer and the tractor.

Reply 5

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Original post by Nagromicous

Are you just asking us to do your homework for you or do you need help with something

I need help working out the tension and time taken? I've worked out the mass

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Original post by ayman98763

I need help working out the tension and time taken? I've worked out the mass

What is the resultant force, mass and acceleration of the trailer?

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Original post by squidge_gt

What have you got so far?

ive got that 11080-600-160=0.8*m
and then i got the mass as 12900Newtons

Reply 8

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Original post by Zelerate

What is the resultant force, mass and acceleration of the trailer?

ive got the mass as 12900newtons
acceleration is 0.8ms^-2
and i think resultant force is 11080-600-160=10320 newtons

Reply 9

If you have the mass of the tractor + trailer (5m) to be 12900, then you can figure out m. Then consider the tractor forces: 11080-160-T=4m * 0.8

(edited 2 years ago)

Reply 10

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Original post by Zelerate

If you have the mass of the tractor + trailer (5m) to be 12900, then you can figure out m. Then consider the tractor forces: 11080-160-T=m * 0.8

so 11080-600-T = 2580*4
10480-T =10320
so tension is 160 Newtons
is that right?

Reply 11

Original post by ayman98763

so 11080-600-T = 2580*4
10480-T =10320
so tension is 160 Newtons
is that right?

Multiply 2580*4 by 0.8.

Reply 12

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Original post by Zelerate

Multiply 2580*4 by 0.8.

2580*4=10320*0.8=8256
10480-8256=2224 newtons
so 2224 newtons as tension.
Any idea about working out time taken, would that involve suvat equations?

(edited 2 years ago)

Reply 13

Original post by ayman98763

2580*4=10320*0.8=8256
so 8256 newtons as tension.
Any idea about working out time taken, would that involve suvat equations?

11080 - 160 - 2580*4*0.8 = T = 2664.

For the time taken, it would indeed involve suvat equations as the acceleration is constant. v = u + at would be useful here. Since you know the force and the mass, you can work out the acceleration.

Reply 14

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Original post by Zelerate

11080 - 160 - 2580*4*0.8 = T = 2664.

For the time taken, it would indeed involve suvat equations as the acceleration is constant. v = u + at would be useful here. Since you know the force and the mass, you can work out the acceleration.

so i converted kmh^-1 to ms^-1

s
u = 5ms-1 f=ma 10320/12900=0.8 i just get the same acceleration
v = 3.333ms-1
a =0.8
t ?

Reply 15

Original post by ayman98763

so i converted kmh^-1 to ms^-1

s
u = 5ms-1 f=ma 10320/12900=0.8 i just get the same acceleration
v = 3.333ms-1
a =0.8
t ?

Using F = ma (and a = F/m), the acceleration of the trailer should be -600/2560 as the tension no longer acts on it, and the mass is one fifth of 12900 (5m / 5)

Also, as the speed is going from 18 km/h to 9 km/h, shouldn't your value of v should be 2.5?

Reply 16

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-600/12900/5= -600/2580 =-10/43

v=u + a t
2.5= 5 +(-10/43)t
-2.5/-10/43 =1075ms-1

Reply 17

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