A screw has a head diameter of 0.812 cm and a thread width of 0.318 cm. What is the ideal mechanical advantage?

What is the average speed of a car that travels 40 mph for 1 hour and 60 mph in another hour?

Does anyone know how to solve this problem? i really need . i made an attempt but i just cant get it. a metal rod is 25.000 cm long at 25.0 degrees celsius. when heated to 102.0 degrees celsius, it is 25.054 cm long. what is the coefficient of linear expansion for this metal.

Which is an example of an exothermic process?