Jim pushes hard on a rock that weighs 500 pounds. He pushes with a force of 50 pounds, but the rock doesn't move. How much work did Jim do? ---> Please answer and explain it!! I can't understand this question! Thank you so much!

Ahorizontal wire is tied to supports at each end and vibrates in its second-overtone standing wave. the tension in the wire is 5.00 n, and the node-to-node distance in the standing wave is 6.28 cm. (a) what is the length of the wire? (b) a point at an anti- node of the standing wave on the wire travels from its maximum upward displacement to its maximum downward displacement in 8.40 ms. what is the wire's mass?

Curious carl calculated the density of a cube to be 4.50 g/cm3. what is the density of the cube in g/l?

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.