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mechanics a level

hi, could i have some help pleaseeee, i am so confused
7. In this question, the unit vector i is horizontal and the unit vector j is vertically upwards. All forces are in newtons.

A small, heavy box is suspended in mid-air and is held in equilibrium by the tension in a light inextensible string and a horizontal force, as shown in the diagram.

The tension in the string is T1, where T1 = 30i + 49j. The horizontal force is F1, where F1 = pi.

(i) Write down the value of p and show that the mass of the box is 5 kg. [3]

(ii) Calculate the magnitude of T1 and the angle that T1 makes with the horizontal.
[3]
Another force F2 = 48i – 87j is now applied to the box. The force F1 still acts and the box is still in equilibrium.

(iii) The new tension in the string is T2 = ai + bj. Calculate the values of a and b. [2]

Original post by dazedconfused

Have you tried equating i components, then j components?

Reply 3

dazedconfused

Original post by Muttley79

Have you tried equating i components, then j components?

for part i??

Reply 4

Muttley79

Original post by dazedconfused

for part i??

Yes

Reply 5

dazedconfused

Original post by Muttley79

Yes

i feel really annoying but could you please explain by what you mean when you say equating the i and j components?? i would appereciate it alot :smile:

Reply 6

Muttley79

Original post by dazedconfused

i feel really annoying but could you please explain by what you mean when you say equating the i and j components?? i would appereciate it alot :smile:

The tension in the string is T1, where T1 = 30i + 49j. The horizontal force is F1, where F1 = pi.

I can't do it for you, it's against the rules, but put the i part of T1 = to the i part of F1.

Then the j component must equal what other force?