Angelina Jolie

Physics problems..please help. dont even how to start the problem?

1) What is wrong with the road sign: Memphis 7 miles (11.263 km) ?
2) Force F has units of kg m/s2 . The force of gravity between at object of mass M and a second object of mass m separated by a distance r is given by F=-GMm/ r2 , where G is the gravitational constant. What are the units of G.
3) A man of mass M steps on an analog scale. His mass is measured to an accuracy ?M. A second man
of mass m uses a different scale. Here his mass m is measured to an accuracy of ?m.
(a) Assuming that the two measurements errors are random and uncorrelated (i.e. how well we can read the scale lines on the scale) what is the error in the quantity Mtotal = m + M.
(b) Now they both step on the same digital scale that can be read very precisely. However, there is a
calibration uncertainty of 1% in the scale’s readout. What is the systematic error in Mtotal=m+M that results form the uncertainty in the calibration of the scale.
4)Force F has units of kg m/s2 . The electric force between an object of
charge Q and a second object of charge q separated by a distance r is given by F= k Qq/ r2 , where k is a constant. In order to determine the charge of q, the electric force between the two charges is
measured to accuracy ?F, Q is known to a accuracy of ?Q, and r is known to an accuracy ?r.
Assuming that all these errors are uncorrelated, what is the fractional error in the determination of q
(Fractional error = is ?q/q ) . Start with q= F r2/ (kQ)