Mechanics help!!! (1 Viewer)

[philk_93]

Hey guys could u help me with a really question, sorry my brain doesnt seem to work today:
A mass of 10 kg is pulled along the horizontal by a chain making an angle of 30 degrees with the horizontal. If the tension in the chain is 50 N, find the acceleration of the body and the magnitude of the normal reaction.
The answer for the acceleration is 4.33m/s^2 and for the normal reaction it is 75N.

Thanks for any help in advance

 

[sickmyducks]

F=ma
a=F/m
=Tcos30/10
=4.33ms-2

Resolving vertical forces:

N+Tsin30=mg
assuming g=10ms-2,
N=10x10 - Tsin30
=75N

 

[descartes]

Resolve your forces horzontally and vertically;

Tension will have a vertical component of 50sin30 and a horizontal component of 50cos30

Normal force and mg are purely vertical forces

vertical F:

my''= N - mg + 50 sin30

but the forces are balanced vertically i.e. my'' = 0

0 = N - mg + 50 sin30
N = mg - 50 sin30
N = (10)(10) - (50)(0.5)
N = 75

horizontal F;

mx'' = 50cos30
x'' = 5cos30
x'' = (5)(sqrt(3)/2)
x'' = 4.33