Police radar guns work by measuring the change in frequency of a reflected pulse of electromagnetic waves. A gun reads correctly only if a car is moving directly toward or away from the person making the measurement. Explain why this is so. Is a highway patrol officer likely then to overestimate or underestimate the speed at which your car is moving

yup its correct its: c) b b

grav force prop 1/r squared 2r all squared is 4rsquared 1/4rsquared quartered

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27

i don't understand. explain it clearly