Modern Physics

4. What are the strength and direction of an electric field that will balance the weight of a 1 g plastic sphere that has been charged to -3 nC?

Question 1 A 25-kg skier starts from rest at the top of a rough (not frictionless) 33° slope and travels 179 m along the slope, acquiring a speed of 26 m/s along the way. How much work is done by friction on the skier? (Note the x103 below.)

Repeat the analysis of barometric pressure from equations (17) - (20) but account- ing for the fact that the gravitational potentiall is actually

The Global Positioning System, GPS, works by triangulating your position from the known positions of multiple satellites. Since those satellites are moving, to know their positions we must know what time the measurement is being made. To know the time, each satellite has a good clock. Explain why Einstein's relativity is important in this situation.

a wheel of mass m and radius R is rolling down a wedge without slipping. The wedge has mass M, angle α, and is free to slide on a smooth horizontal table. Ignore friction between the wedge and the table. (a)find the Euler-Lagrange equations of motion. (b) assuming that the wheel is gently placed on top of the wedge att= 0,determine the speed of the wheel when it reaches the bottom of the wedge.

Q6- Depict and describe the function of Light Emitting diode (LED), Photodiode, and Optical fibre?

4) [Electric Potential Energy] A double-helix of DNA (deoxyribonucleic acid) acts like a spring and compresses upon becoming ionized and charged at the both ends. The double helix is 2.17μm long before charging, and compresses 1.5% after the DNA double helix becomes charged with negative charge of -3e at one end and a positive charge of +2e at the other end. For simplicity you may assume the DNA in vacuum. (a) What are the magnitude and direction of the electric field at the middle of the double helix in the compressed state? (b) What's the electric potential energy of the double helix when the compression just starts and after the compression completes? (c) If the compressed state is a mechanical equilibrium, what are the magnitude and direction of the elastic force at the two ends in the compressed state?

1. Put the following components of an ultrasound machine in order of their function:

A child pulls on a little red wagon with a horizontal force of 71 N. The wagon moves horizontally a distance of 47.7 m in 3.2 minutes. Calculate the average power generated by the child in that time frame.

7. a) What is the electric field at point P? b) An electron is placed at point P, what is the resulting force on the electron (magnitude and direction)? 6 nm q=-9pC