Two masses (mA= 2 kg, mB= 4 kg) are attached to a (massless) meter stick, at the 0 and 75 cm marks, respectively.

c.) Now, if mass B was removed, how much force would need to be exerted at the 100 cm mark in order to keep the meter stick level*?
? N

d.) Now, if mass B was removed, and no additional force was supplied, calculate the size of the angular acceleration of the meter stick at that instant*.
? rad/s2

2 answers

There has to be a center of rotation it seems to me, and it is not specified.
I think the assumption is to assume that the stick is level with masses A and B attached.
Thus if the balance point is x cm from the zero
2x=4(75-x) so x=50 cm

Assuming this then to keep it level
2 kg are needed at 100 cm.
If g=10 m s^-2 then the force is 20 N.

Not a very well worded question in my view.