Constant Acceleration and Resolution of Forces

[FaraDazed]

Homework Statement

A block of concrete 5kg is initially at rest on a smooth (frictionless) horizontal surface. It is then pulled along by a constant force A, inclined at 45° from the horizontal. In the first 5 seconds of motion, the block moves a distance of 10m.

A: Find the acceleration of the body
B: Find the magnitude of the force A
C: Find the normal reaction force

Homework Equations

$v=u+at\\<br /> s=\frac{1}{2}(u+v)t\\<br /> s=ut+\frac{1}{2}at^2\\<br /> v^2=u^2+2as\\<br /> F=ma\\<br /> R=mg\\$

The Attempt at a Solution

I wasn't quite sure how to start but with the known variables I started with equation 2 from above and then the rest is dependent of whether I started it correctly.
$Part A:\\<br /> s=\frac{1}{2}(u+v)t\\<br /> 10=0.5(0+v)5\\<br /> 10=2.5v\\<br /> v=4\\<br /> .\\<br /> v=u+at\\<br /> 4=0+a5\\<br /> a=\frac{4}{5}=0.8\\<br /> .\\<br /> Part B:\\<br /> Acos45=ma\\<br /> Acos45=5 \times 0.8\\ <br /> 0.71A= 4\\<br /> A=\frac{4}{0.71}=5.63N\\<br /> .\\<br /> Part C:\\<br /> R+Asin45=mg\\<br /> R+5.63sin45=5 \times 9.8\\<br /> R+3.98=49\\<br /> R=49-3.98=45.02N$

The figures I got just seem low to me, any help or advice/pointers is greatly appreciated.

 

[Doc Al]

Looks good to me.

 

[FaraDazed]

Looks good to me.

OK, thank you :) .