an object is thrown straight up. which of the following is true abought the sign of workdone by the force of gravity on the obje
1 answer:
Answer:
Upward: Negative
Downward: Positve
Explanation:
Let upward be positive
We want to find the work done on the object upwards.
The equation of work done due to gravity is
It is read as force of gravity times displacement times cos of the angle between the force and displacement.
Since gravity is happening down of the center of mass and the displacement is upwards, the angle is 180° so
Cosine of 180 is -1
so
If we go downwards, the sign will be positive because cos(0)=1
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The acceleration of the electron is larger than the acceleration of the proton.
The reason for this is that the mass of the electron is smaller (about 1000 times smaller) than the mass of the proton. The two particles have same charge (e), so they experience the same force under the same electric field E:
However, according to Newton's second law, the force is the product between the mass particle, m, and its acceleration, a:
which can be rewritten as
we said that the force exerted on the two particles, F, is the same, while the mass of the electron is smaller: therefore, from the last formula we see that the acceleration of the electron will be larger than that of the proton.
The reason for this is that the mass of the electron is smaller (about 1000 times smaller) than the mass of the proton. The two particles have same charge (e), so they experience the same force under the same electric field E:
However, according to Newton's second law, the force is the product between the mass particle, m, and its acceleration, a:
which can be rewritten as
we said that the force exerted on the two particles, F, is the same, while the mass of the electron is smaller: therefore, from the last formula we see that the acceleration of the electron will be larger than that of the proton.
Case d) has the strongest gravitational force
Explanation:
The magnitude of the gravitational force between two objects is given by the equation:
where :
is the gravitational constant
m1, m2 are the masses of the two objects
r is the separation between the objects
a) For this pair of objects:
m1 = 10 kg
m2 = 2 kg
r = 30 km = 30,000 m
So the gravitational force is
b) For this pair of objects:
m1 = 10 kg
m2 = 10 kg
r = 30 km = 30,000 m
So the gravitational force is
c) For this pair of objects:
m1 = 2 kg
m2 = 2 kg
r = 10 km = 10,000 m
So the gravitational force is
d) For this pair of objects:
m1 = 10 kg
m2 = 10 kg
r = 10 km = 10,000 m
So the gravitational force is
Therefore, the strongest gravitational force is in case d).
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The new gravitation force at the new location is 40 N
Explanation:
The weight of the astronaut is given by the equation
(1)
where
m is the mass of the astronaut
g is the acceleration of gravity
The acceleration of gravity at a certain distance from the centre of the Earth is given by
where G is the gravitational constant and M is the Earth's mass. So we can rewrite eq.(1) as
When the astronaut is on the Earth's surface, (where R is the Earth's radius), so his weight is
Later, he moves to another location where his distance from the Earth's surface is 3 times the previous distance, so the new distance from the Earth's centre is
Therefore, the new weight is
Which means that his weight has decreased by a factor 16: therefore, the new weight is
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