A carpenter uses a crowbar to remove the top of a box. If the top has a resistance of 500 Newtons, and the carpenter applies an effort force of 100 Newtons, what is the mechanical advantage of the crowbar?

Can somebody explain to me how newton's 3rd law relates to momentum? ~ap physics 1

What sort of waves exhibit the doppler effect?

Two technicians are discussing a starter that clicks repeatedly when the key is turned to the crank position. technician a says the solenoid hold-in winding is open. technician b says the solenoid pull-in winding is open. who is correct?