Answer:
F = 4000 N
Explanation:
given,
mass of rocket (M)= 5000 Kg
10 Kg gas burns at speed (m)= 4000 m/s
time = 10 s
average force = ?
at the end the rocket is at rest
by conservation of momentum
M v + m v' = 0
5000 x v - 10 x 4000 = 0
5000 v = 40000
v = 8 m/s
speed of rocket = 8 m/s
now,
we know
change in momentum = F x Δ t
F = 4000 N
Hence, the average force applied to the rocket is equal to F = 4000 N
Answer: c. Generally, metals are ductile.
Explanation:
From the options given in the question, the correct statement is that"Generally, metals are ductile.
Ductility of a metal simply means that a metal can be plastically deform before it is then fractured. It implies that metals can be drawn to thin wires. The only exception we have in this case is mercury.
Since we ride along with the Earth while it's doing whatever it does,
the Earth's rotation causes our eyes to constantly point in a different
direction.
If we try to keep watching one star, we have to keep changing the
direction of our eyes to keep looking at the same star.
We can't feel the Earth rotating, so our brains say that the star ... and
the sun and the moon too ... is actually moving across the sky.
They both release greenhouse gases, I think
