A cannon sits on a stationary railroad flatcar with a total mass of 1000 kg. when a 10 kg cannonball is fired to the left at a speed of 50 m/s, what is the speed of the flatcar

0.5 m/s

Explanation:

From Newton's Third law of motion,

Momentum of the cannon = momentum of the flatcar.

mv = MV Equation 1

Where m = mass of the cannon, v = velocity of the cannon, M = mass of the flatcar, V = Velocity of the flat car.

make V the subject of the equation

V = mv/M Equation 2

Given: m = 10 kg, v = 50 m/s, M = 1000 kg

Substitute into equation 2

V = 10×50/1000

V = 500/1000

V = 0.5 m/s

Hence the speed of the flatcar = 0.5 m/s

u=13

v=30

s/t=u+1\2at

=13+431/2

=13+265.5

=278.5

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.