Posted by **anonymous** on Wednesday, March 3, 2010 at 5:51am.

Three forces acting on an object are given by F1 = ( - 1.85i + 2.50j) N, F2 = ( - 5.10i + 3.25j ) N, and

F3 = ( - 45.0i + 48.0j ) N. The object experiences an acceleration of magnitude 3.75 m/s2.

(a) What is the direction of the acceleration?

_________° (from the positive x axis)

(b) What is the mass of the object?

_________ kg

(c) If the object is initially at rest, what is its speed after 17.0 s?

_________ m/s

(d) What are the velocity components of the object after 17.0 s?

( ________ i + _________ j ) m/s

- physics -
**drwls**, Wednesday, March 3, 2010 at 6:45am
This is an exercise in adding vectors. The ratio of components in vector sum will provide the fdirection information you need. The mass is the ratio of the force magnitude to the acceleration.

For (c), assume the initial speed is zero and multiply the acceleration and time interval. For (d), multiply the vector acceleration by the time.

Show your work if further assistance is needed.

- physics -
**Anonymous**, Tuesday, October 12, 2010 at 8:38pm
a) direction of acceleration in the same way as resultant force, hence

Fr=F1+F2+F3=(-1.85-5.10-45.0)i+(2.50+3.25+48.0)j= -51.95i+53.75j [N]

θ=tanˉ¹(53.75/-51.95)=134°.

b) F=ma --- m=F/a --- (√((-51.95)^2+53.75^2))/3.75=19.9kg

c)Vf=Vi+at=0+3.75*17=63.75m/s

d)F=ma --- a=F/m ---āx=F̅x/m --āy=F̅y/m

ā=āx + āy

V̅f=V̅i+āt=0+((-51.95/19.9)i+(53.75/19.5)j)*10

V̅f=((-51.95/19.9)*10)i+(53.7/19.5)*10)j

V̅f= -26.1i+27.5j

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