A spacecraft left Earth to collect soil samples from Mars. Which statement is true about the strength of Earth’s gravity on the
1 answer:
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Answer:
Change in mechanical energy = work done by friction
so it is equal to
Explanation:
As we know that change in mechanical energy must be equal to the work done by non conservative forces only
So here when block moves down the inclined plane then the work done by friction force is given as
here we have
here we know that
so we have
Now the friction force on the block is given as
now work done by the friction is given as
The astronaut will take 300 seconds
Explanation:
We can solve this problem by using the law of conservation of momentum.
In fact, the total momentum of the astronaut+object system must be conserved.
Initially, they are both at rest, so their total momentum is zero:
After the astronaut throws the object, their total momentum is:
where:
M = 80 kg is the mass of the astronaut
V is the final velocity of the astronaut
m = 500 g = 0.5 kg is the mass of the object
v = 8.0 m/s is the velocity of the object
Since momentum is conserved, we can write
And solving for V,
Which means that he starts moving at 0.05 m/s in the direction opposite to the object.
Now the astronaut needs to cover a distance of
d = 15.0 m
And his speed is
v = 0.05 m/s
Therefore, the time taken is
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1) The mass of the continent is
2) The kinetic energy of the continent is 1683 J
3) The speed of the jogger must be 6.57 m/s
Explanation:
1)
The continent can be represented as a slab of size
and depth
So its volume is
We also know that the density of the continent is
Therefore, we can calculate its mass as:
2)
The kinetic energy of the continent is given by
where
m is its mass
v is its speed
We have already calculate its mass, while the speed is
v = 3.2 cm/year
We have to convert into SI units first, as follows:
The mass is
So, the kinetic energy of the continent is
3)
Here we have a jogger having the same kinetic energy of the continent, so
And the kinetic energy of the jogger can be expressed as
where
m = 78 kg is the mass of the jogger
v is his speed
We can therefore re-arrange the equation to find the speed of the man, and we get:
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