Explain why a meteorite burns up as it enters the earth's atmosphere. Using ideas about work and energy...
2 answers:
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Answer:
At the focus
Explanation:
In car head lights concave mirrors are used. The light bulbs in these headlights are place along the principal axis as shown in the figure. On this Principal axis light bulbs are place at the Focus to get maximum brightness. As from the figure we can conclude that light rays coming from infinity converse at focus thus, giving maximum brightness.
1) -0.5 m/s
We can solve the first part of the problem by using the law of conservation of momentum. In fact, the total momentum of the cannon - shell system must be conserved.
Before the shot, both the cannon and the shell are at rest, so the total momentum is zero:
After the shot, the momentum is:
where
M = 2000 kg is the mass of the cannon
m = 10 kg is the mass of the shell
v = 100 m/s is the velocity of the shell (we take as positive the direction of motion of the shell)
V = ? is the velocity of the cannon
Since momentum is conserved, we can write
And solving for V, we find the velocity of the cannon:
where the negative sign indicates that the cannon moves in the direction opposite to the shell.
2) 0.5 m
The motion of the cannon is a uniformly accelerated motion, so we can solve this part by using suvat equation:
where
v is the final velocity of the cannon
u = 0.5 m/s is the initial velocity of the cannon (now we take as positive the initial direction of motion of the cannon)
is the deceleration of the cannon
s is the distance travelled by the cannon
The cannon will stop when v = 0; substituting and solving the equation for s, we find the minimum safe distance required to stop the cannon: