Physics Answers

The orbit of a satellite was at an altitude of about 400 km and an inclination of 51°. It's starting mass was 50kg. What is the gravitational force

The most powerful 5G antennas work with a power of 120W. Assume that the human head is a sphere with a radius of 10 cm and that the human body is made of water. For simplicity, you can also assume that the antenna transmits radio waves in all directions evenly.

a) Estimate the upper limit (worst case scenario) of how much energy is captured by the human head if we are standing just below the antenna (5 m from the antenna). Indicate which laws and concepts you used in the calculation.

b) Estimate how long it would take to stand under the antenna to warm the brain by 0.1 ° C if all cooling modes are neglected.

c) List and describe as many ways as possible in which the human brain dissipates heat to the environment.

One-meter-long coaxial cable is incorrectly connected to the output device, so part of the signal bounces back on the connection. Determines the speed of the signal along the wire if we see echoes in the signal with a delay of 10 ns. Determines the wavelength of the signal in the cable if its frequency is 10 GHz.

For adiabatic ideal gas near room temperature, what fraction of heat supplied is available for external work. If the gas is expanded at a constant pressure? At a constant temperature?

A 2-kg mass is held at rest at the top of an incline that make a 400 angle with the ground. The incline is 1.5 m long and the coefficient of kinetic friction µk = 0.2. When the mass is released, slides down the inclined with uniform acceleration.

A helium gas is at pressure of 1atm and temperature of 0°C. If its pressure is dropped to its initial pressure, when its volume is kept constant. (a) calculate the work done by the gas. (b) what is the final temperature of the gas. (b) what is the work done by the if its volume becomes twice as initial volume and it return to its initial temperature.

9.2.Two point charges in air at a distance of 20 cm from each other

interact with a certain force. At what distance from each other should

these charges be placed in oil to'obtain the same force of interaction?

Ruel is on his way to the grocery store riding his motorcycle. He started at rest in front of their house. He then travels ahead so that his distance from where he started is given by the equation:

  x(t)=(2.4ms2)t2−(0.120ms3)t3

a. Calculate the average velocity of the motorcycle for the time interval t=0 sec to t=10 sec.

b. Determine the instantaneous velocity at t=0 sec and t=5 sec

9.1.Find the force of attraction betweenthenucleus of a hydrogen

atom and an electron. The radius of the hydrogen atom isO.5x10-8cm

and the charge of the nucleus is equal in magnitude and opposite in

sign to that of the electron.

A steel tape is calibrated at 20 degree Celsius on a day when the temperature is -15 degree Celsius.what will be the percentage error of the tape