Amachine with a mechanical advantage of 10 is used to produce an output force of 250 newtons. what input force is applied to this machine

What sort of waves exhibit the doppler effect?

What are the similarities & differences between a thermistor and a light dependent resistor in physics?

The horizontal blue line through the middle of the lens is called the optical axis. as the lamp is moved above or below the axis, keeping the horizontal distance to the center of the lens constant, how does the horizontal distance from the lens to the image change?