What physical characteristic is the same for a particular substance regardless of the sample size .
1 answer:
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The gravitational force acting on the man is 800 N towards the Earth's centre
Explanation:
The weight of an object on the Earth is exactly the gravitational force exerted by the Earth on the object.
The gravitational force exerted by the Earth on an object located at the Earth's surface is given by:
where
G is the gravitational constant
M is the Earth's mass
m is the mass of the object
R is the radius of the Earth
And the direction of the force is towards the Earth's centre.
Since G, M and R are constant, they are grouped into a single constant called g, acceleration of gravity:
therefore the gravitational force can be rewritten as
And this is the usual equation that we use to calculate the weight of an object.
Therefore, weight and gravitational force acting on an object on Earth are the same thing: so, the gravitational force acting on the man is equal to his weight, 800 N, and it acts towards the Earth's center.
Learn more about weight and gravitational force:
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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: