please help me!!physics?

Question

A 1.0 kg ball hangs from the ceilimng of a truck by a 1.0m long string. The back of th etruck, where you are riding with the ball, has no window and is completely soundproof.truck travels along an exceeding smooth test track, and you feel no bumps or bounces as it moves. only instrument is the meter stick, a protractor and a stopwatch.
a. driver tells you that the truck is either at rest or moving forward at a sterady speed of 5m/s. can you deternmine which it is? if so how??
b.then the driver tells you that the truck is either moving forward at a steady speed of 5m/s or it is accelerating. can you det. which is it?
c.truck has been accelerating forwards at 5m/s^2 long enough for the ball to achieve a stead position. does the ball have an acceleration? if so, what are the magnitude and direction of the ball's accel?
d. FBD that shows all forces acting on the ball as the truck accelerates.
e. ball makes a 10degree angle with vertical. det truck's velocity/acceleration??

Answer 1

Interesting problem

a) Did you say the truck is moving or standing on a well leveled surface? In that case the string is perpendicular to the celling. Protractor reads 0.

b) Hmmm... steady speed or standing still? If protractor reads 0 then one guess is as good as the other.

c) If the truck is moving with a constant acceleration the protractor will read
A=arctan ( F/mg)
where F=ma or
A=arcSin(ma/mg)= arcSin(a/g)
A=arcSin(5.0/9.81)=30 deg
Okay so may be I jumped to a conclusion
The ball will move apposite of the truck's direction
and you can test the driver by computing a

ma=mgsin(A)
so a= g sin(A)

d) FBD Is it Federal Bureau of Detention (poor joke)

A string makes an angle A with the vertical or measure the angle B it males with the ceiling and A=90-B.
The W=mg is down and is being resolved into F=W sin(A) and T=Wcos(A)

e) Velocity could be tough unless you clicked or stopwatch
we know that
a= g sin(A)

so V=at (you did measure time have you not?)

Answer 2

a) no - Newton's Ist Law - there is no way you can distinguish between constant velocity and rest state if you are in the inertial frame (here I assume that in your case constant speed also means constant velocity)
b) yes - if there is a positive acceleration the ball will seem to be moving toward the front of the truck from your point of view
c) I'm guessing yes
d) upward tension (has x and y components), downward force of gravity (only in -y direction = mg) and fictional force
e) sum of the forces = ma
tension + weight = ma (as vectors)