What is destructive interference?
2 answers:
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Her mass is still 70 kg
Explanation:
The mass of an object is an intrinsec property of the object that gives a measure of the "amount of matter" inside the object.
Being an intrinsec property, it depends only on the object itself, not on its location: therefore, the mass of an object is always the same in different locations. Therefore, the mass of the astronaut in the spacecraft is still the same as if she was on the earth, 70 kg.
On the contrary, the weight of an object is the force of gravity acting on the object, and it is given by
where
m is the mass
g is the acceleration of gravity
While m is always the same, the value of g changes based on the location: therefore, the weight of an object changes depending on the location.
Learn more about gravity:
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Answer:
2. The metal surface exerts less frictional force because there are fewer bumps and irregularities on it than there are on the concrete.
Explanation:
Frictional force is a force that is exerted between two surfaces in contact with each other. Frictional force always opposes the direction of relative motion of the two surfaces: for instance, for a ball moving along a surface, the force of friction exerted by the surface on the ball points opposite to the direction of motion of the ball.
The magnitude of the frictional force for a ball moving on a flat surface is given by
where
is the coefficient of friction
m is the mass of the ball
g is the acceleration of gravity
The value of depends on the type of surface involved. In particular, a smooth surface has a smaller value of
, while a rough surface will have a bigger value. In this case, we are comparing a smooth metal surface with concrete: since the metal surface has fewer bumps and irregularities than concrete, it has a smaller value of coefficient of friction, so it exerts less frictional force than concrete.