Answer:
D) momentum of cannon + momentum of projectile= 0
Explanation:
The law of conservation of momentum states that the total momentum of an isolated system is constant.
In this case, the system cannon+projectile can be considered as isolated, because no external forces act on it (in fact, the surface is frictionless, so there is no friction acting on the cannon). Therefore, the total momentum of the two objects (cannon+projectile) must be equal before and after the firing:

But the initial momentum is zero, because at the beginning both the cannon and the projectile are at rest:

So the final momentum, which is sum of the momentum of the cannon and of the projectile, must also be zero:

Answer: Heat transfer due to emission of electromagnetic waves is known as thermal radiation.
Explanation: Heat transfer through radiation takes place in form of electromagnetic waves mainly in the infrared region. Radiation emitted by a body is a consequence of thermal agitation of its composing molecules.
Answer:
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Answer:
The one with highest velocity
Explanation:
The momentum of an object is given by

where
m is the mass of the car
v is the velocity of the car
In this problem, we have two identical cars: identical means they have same mass, so

The momentum of car 1 is

while the momentum of car 2 is

By comparing the two expressions, we see that the car with greatest momentum is the one with highest velocity, since the mass is the same.