Complete Question
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Answer:
The velocity is
Explanation:
The kinetic energy of the 9 kg can be determined by these expression
Kinetic energy of 9 kg block = initial energy stored - energy lost as a result of friction
Now to obtain the initial energy stored
Let U denote the initial energy stored and

Where x is the length the spring is displaced
k is the force constant of the string


Now referring to the formula above
i.e Kinetic energy of 9 kg block = initial energy stored - energy lost as a result of friction



and we are told that coefficient of friction = 0.4 and the mass is 9 kg ,the acceleration due to gravity
this displacement length of spring = 0.6
Therefore 
A. Between asteroids C and D because gravitational attraction is greatest with increased mass.
Angle of projection: 28 degrees or 62 degrees
Explanation:
A projectile consists of two independent motions:
- A uniform motion along the horizontal direction
- A uniformly accelerated motion along the vertical direction
From the equations of motion, it is possible to derive an expression for the range of a projectile, which is:

where:
u is the initial speed
is the angle of projection
is the acceleration due to gravity
For the projectile in this problem, we have:
d = 15 km = 15,000 m is the range
is the initial speed
Solving the equation for
, we find the possible angle:

Which gives two values of the angle:

Learn more about projectile:
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