Answer:
approximately 30 degrees
Explanation:
If it takes the cannonball 2 seconds to reach the maximum height, we can use the analysis of the vertical component of the velocity and the fact that the acceleration of gravity is the one acting opposite to this initial vertical component 
of the velocity. We know as well that at the top of the trajectory, the vertical component of the velocity is zero, and then the movement starts going down in it trajectory. So, the final velocity for the first part of the ascending movement is zero, giving us the following equation for the velocity under an accelerated movement (with acceleration of gravity "g" acting):
By knowing the vertical component of the initial velocity (19.6 m/s), and the actual magnitude of the total initial velocity (40 m/s), we can calculate what angle was the initial velocity vector forming above the horizontal. We use for such the fact that the sine of the angle relates the opposite side of a right angle triangle with the hypotenuse, and solve for the angle using the arcsin function:
which tells us that the closer answer shown is 
Answer:
The heat energy required, Q = 6193.8 J
Explanation:
Given,
The mass of ice cube, m = 18.6 g
The heat of fusion of ice, ΔHₓ = 333 J/g
The heat energy of a substance is equal to the product of the mass and heat of fusion of that substance. It is given by the equation,
<em> Q = m · ΔHₓ joules</em>
Substituting the given values in the above equation
Q = 18.6 g x 333 J/g
= 6193.8 J
Hence, the heat required to melt the ice cube is, Q = 6193.8 J
Answer:
in rocket flight become balance and unbalanced sometimes
Explanation:
The reason why Marina sees the colour red, white and blue or the original colour of the American flag is that because of a phenomenon known as Afterimage. The retina in our eyes have mainly three receptors that are colour sensitive known as cones. These receptors can perceive the colour green, red and blue. Now when we look or stare at a particular colour for a long time, what happen is that our retina becomes tired and they ignore the colours that stared at. And now they work to form other colours at the retina just like the way when we produce other colour from the primary colour.
If the red receptor gets exhausted we will see the colour red. Likewise when we see the colour orange when we stare at the colour blue.
This explains the optical illusion of the American flag.
