If the desk doesn't move, then it's not accelerating.
If it's not accelerating, then the net force on it is zero.
If the net force on it is zero, then any forces on it are balanced.
If there are only two forces on it and they're balanced, then they have equal strengths, and they point in opposite directions.
So the friction on the desk must be equal to your<em> 245N</em> .
Answer
Given,
Average speed of Malcolm and Ravi = 260 km/h
Let speed of the Malcolm be X and speed of the Ravi Y.
From the given statement

....(i)
....(ii)
Adding both the equations
3 X = 600
X = 200 km/h
Putting value in equation (i)
Y = 520 - 200
Y = 320 Km/h
Speed of Malcolm = 200 Km/h
Speed of Ravi = 320 Km/h
Answer:
An Atom's individual speed will change as it collides with other atoms, so we have to use an average.
Explanation:
In a gas a single atoms does an assortment of things during its time in the gas—sometimes it collides with an other atom gaining a lot of speed, sometimes losing a lot of speed in the collision, and sometimes just moving freely. Therefore: the motion of one individual atom is unpredictable, and it cannot be representative of all the the atoms in a gas, which is why we must average over all speeds of all atoms to find an average speed that allows us to calculate other quantities like temperature and pressure of the gas.
Hence, the second option <em>"an Atom's individual speed will change as it collides with other atoms, so we have to use an average" </em>stands correct.
C. thermal energy added to the engine minus the waste heat.
The law exemplifies conservation of energy.
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