Why is the efficiency of a machine always less than 100 percent

The ecliptic is the annual path of the Sun relative to the background stars. the shortest day of the year, when the Sun takes its lowest path in the sky. the location of the North Star on the celestial sphere.

Which state of matter has the highest density

Raindrops fall vertically at 7.5 m/s relative to the Earth. What does an observer in a car moving at 20.2 m/s in a straight line measure as the velocity of the raindrops? (Assume the car is moving to the right and that the + x-axis is to the right.

What nuclear reaction is the energy source of a white dwarf? a. carbon and helium fusing into oxygen b. none c. helium fusing into carbon d. hydrogen fusing into helium e. oxygen fusing into silicon

How much power does a 850 watt power supply use?

A car is moving with a speed of 22 m/s. The driver then brakes, and the car comes to a halt after 6.5 s. What is the distance covered by the car after the driver brakes, until it comes to a stop? A) 36 m B) 72 m C) 140 m D) 210 m

Which of the following best explains why an explosive charge in a cannon can cause a cannonball to fly out of the cannon with a high velocity? A. because chemical potential energy can convert to gravitational potential energy B.

Distance divided by time what is velocity

The decay constant of a radioactive nuclide is 4.6 x 10^-3 s^-1. What is the half-life of the nuclide? 2.5 min 2.0 min 1.4 min 3.6 min 3.1 min

A furlong is an old british unit of length equal to 0.125 mi, derived from the length of a furrow in an acre of ploughed land. a fortnight is a unit of time corresponding to two weeks, or 14 days and nights.