Physics

Doppler Effect and a Motion Detector

A stationary motion detector sends sound waves of 0.120 MHz toward a truck approaching at a speed of 55.0 m/s. assume the speed of sound is 343.0 m/s What is the frequency of the waves reaching the d

Am I doing this Physics question right? (High school, Work and Energy Unit)

What is the power output of an electric motor that lifts an elevator with a mass of 1500 kg at a speed of 0.750 m/s. (1500)(9.81) = 14715 N (14715)(0.75) = 11036.25 W 11036 / 1000 = 11.0 kW-Looks O

Why is it that when you touch something hot, the sensation gets hotter

This is sortof hard to explain. Just then I picked up my mug of hot water by the cup and not by the handle. At first I could hold it, but it felt like it was getting hotter and hotter until I had to l

Is it possible to vary voltage without much power loss

hi, is it possible to vary the voltage from a supply, without using a transformer, or variac? as i have a flyback transformer & driver, and it uses 7A at 40v. it would be handy if i could vary the m

Hows does a thermos keep things hot and cold in terms of conduction, convection and radiation

Conduction: air, and otherbad conductors are kept between the substance inside and outer environment(that is the lining cavity) Convection: air in touch with the substance is sealed(cant really move)

Help with a quick physics problem

A peg on a turntable moves with a constant linear speed of 0.68 m/s in a circle of radius 0.48 m. The peg casts a shadow on a wall. Find the period of the motion of the shadow.-angular velocity=veloci

To cause two waves to interfere completely destructively they have to

A) *have the same amplitude B) *be exactly out of phase C) *one waves peak must align with the others valley D) *be transverse waves E) *all of the above which of these statements apply?(can be as mo

Metabolic rate to joules

Q. For a person with a resting metabolic rate of 1600 Calories in 24 hrs calculate their resting metabolic rate in Watts (joules per second) * an explanation and formula would be sooooooooo helpful-A

Nuclear Yield + Fallout Question (easy, no calculations necessary)

I am doing a project on nuclear chemistry and its relation to nuclear weapons. I am currently at an impasse. I am discussing efficiency in nuclear yield (for example Little Boy only yielded 1% efficie

Without quantum fluctuations would not electron fall into the nucleus

Doesnt that imply that its a more fundamental theory than general relativity?-Time has two properties. Progress(related to evolution) and Event(related to Creation) by turns. and Probability exist b

Equation for force when pulling something with rope

I am not sure what equation to use... I need to figure out the amount of force required to pull something (a box, for example)depending on the angle of the rope... like if it is attached at the top or

Optical physics question!! I know it's easy, but I'm clueless!

A photographer uses a lens with f = 60 mm to form an image of a distant object on the CCD detector in a digital camera. The image is 1.0 mm high, and the intensity of light on the detector is 2.1 W/m^

Lifting force in newtons

A person exercising in the gym lifts a heavy load of mass 50kg through a distance of 0.75m in 0.5 seconds(a) If the strength of gravity is 9.8 N/kg what is the lifting force in Newtons the person must

How much kinetic energy does it have at the top

A block of weight 3.9 {N} is launched up a 30(degree) inclined plane of length 2.20 {m} by a spring with spring constant 2.05 {kN/m} and maximum compression 0.10 {m}. The coefficient of kinetic fricti

How to find V,and I on this circuit

here is the image.see this to understand the problem better. http://oi52.tinypic.com/10pypw9.jpg how to find I2,I3 and V from this?-What you need is ohms law and Kirchhoffs law I1 = I2 + I3(conservat