Answer:
b) The ball is a freely falling body for the duration of its flight.
Explanation:
When an object is thrown upwards, it moves against the direction of gravity. Its velocity decreases with respect to its motion, and zero at the maximum height. After which it falls back to the surface of the earth.
Since the ball moves initially against the force of gravity, its acceleration would be -9.8 m/ at its highest point. Thus since acceleration is constant, the ball is a freely falling body for the duration of its flight.
It depends how the sound travels and the conditions, The speed of sound in dry air, 20°C is 323 m/s
An atom consists of the nucleus (a combination of the proton and neutron) and the electron which orbits the nucleus.
Answer:
A) The work done by the engine is: 6.8MJ/L
B) The fuel efficiency is
Explanation:
A)
We know that the gasoline releases about 3.4*10^7 J of energy for each liter, and about 80% of that energy is lost as heat; it means that the other 20% of the energy released is taken for the engine to do work. In that sense, the work done by the engine is 20% of the 3.4*10^7 J that the gasoline releases for 1 liter, so:
This last can be seen as a conversion factor, where we multiply the energy released by the gasoline by the factor (20 J taken for do work for each 100 J released).
B) We know that the car requires 5.9*10^5 J of work <u>for each km traveled</u>. That is the energy that the car requires, but it is not the energy that you have to give to the car; take in mind that the energy that you put in the car in gasoline liters will be not taken all, but just 20%. Also we know that the work done by the engine for 1 liter of gasoline is 6.8MJ, and that is just the work taken for do work (the useful energy), so we can connect both data:
The first fraction, is the ratio or the proportion of (1 km requieres 5.9*10^5 J); and we multiply by the second fraction , which is the ratio: 6.8*10^6 J of work done for each liter of gasoline.