The beam shown is balanced at its midpoint. The weight of the beam is 40 N. Calculate the unknown force Z, and the length of the beam. The answer is (90N and 1.5m) I know how to get the length but i don’t hope how to get the force :(

Your target variable is δf, the magnitude of the difference in frequency between the waves emitted from the sonar device and the waves received by the device after reflecting off the whale. write an expression for δf in terms of the relevant frequencies using the subscript notation introduced above.

Atomic nuclei of almost all elements consist of

The star betelgeuse is about 600 light-years away. if it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space.b. we'll know it immediately because it will be brighter than the full moon in the sky.c. we won't know about it until 600 years from now.d. none of the above.