Police radar guns measure the speed of moving vehicles by transmitting electromagnetic waves at a vehicle and detecting a doppler shift in the reflected wave. suppose a police radar transmits at a frequency of 26.8 ghz and receives a wave reflected from a car moving toward the radar at 66.0 mph. find the frequency shift

An object weigh 40n in air ,weigh 20n when submerged in water, and 30n when submerged in a liquid of unknown liquid density. what is the density of unknown of liquid?

The substances that are necessary for producing of certain hormones and that store and transport vitamins

Aplayground slide is 8.80 ft long and makes an angle of 25.0° with the horizontal. a 63.0-kg child, initially at the top, slides all the way down to the bottom of the slide. (a) choosing the bottom of the slide as the reference configuration, what is the system's potential energy when the child is at the top and at the bottom of the slide? what is the change in potential energy as the child slides from the top to the bottom of the slide? (include the sign of the value in your answer.)