M1 Help -- Pleeease!

this question is doing my head in, and I bet it's more simple than I think:

Two particles, A and B, are connceted by a light inextensible string which passes over a smooth, fixed peg. The particle A, of mass 0.6 kg, is in contact with a smooth horizontal surface, and the particle B, of mass 0.1 kg, hangs freely above the ground. The system is released from rest with the string taut and A moves towards the peg.

It can be assumed that, during the subsequent motion, A does not reach the peg.

(a) while the particles move freely, the string is taut.
(i) Show that the acceleration of the particles is 1.4 ms/s
(ii) Find the tension in the string
(iii) Find the magnitude of the resultant force ont he peg due to the tension in the string.

Cheers

Reply 1

Jaswarbrick

Nabqueen

this question is doing my head in, and I bet it's more simple than I think:

Two particles, A and B, are connceted by a light inextensible string which passes over a smooth, fixed peg. The particle A, of mass 0.6 kg, is in contact with a smooth horizontal surface, and the particle B, of mass 0.1 kg, hangs freely above the ground. The system is released from rest with the string taut and A moves towards the peg.

It can be assumed that, during the subsequent motion, A does not reach the peg.

(a) while the particles move freely, the string is taut.
(i) Show that the acceleration of the particles is 1.4 ms/s
(ii) Find the tension in the string
(iii) Find the magnitude of the resultant force ont he peg due to the tension in the string.

Cheers

Consider the particle that is hanging freely:

0.1g - T = 0.1a

Now the particle that is on the smooth horizontal surface.

T = 0.6a

Substituting this into the first equation:

0.1g - 0.6a = 0.1a
0.7a = 0.1g
a = 1.4 ms-1

ii) T = 0.6 a
= 0.6 x 1.4
= 0.84 N

Reply 2

Nabqueen

OP

thank you so much!