Explanation:
A star is in equilibrium when the pressures inside the star balance out the force of gravity. The pressure is thermal pressure resulting from the fusion reactions taking place in the star's core. A star stays in equilibrium until the supply of hydrogen in the core is depleted.
In a stable star, the gas pressure pushing out from the center is equal with the gravity pulling atoms inward to the center – when these forces are equal, the star is at equilibrium. Once a star reaches equilibrium for the first time, it will start burning (fusing) hydrogen into helium.
Answer: 26.7 s
Explanation:
Given
Width of the river, = 0.2 km = 200 m
Speed of the rover, = 3 m/s
Speed of the boat, = 8 m/s
From the question, the boat would have to move westward. In moving westward, the angle will be
tan A = 3/8
tan A = 0.375
A = tan^-1(0.375)
A = 21°
Then, the velocity of the boat northward will be
v(north) = 8 cos 21
v(north) = 8 * 0.934
v(north) = 7.47 m/s
Therefore, the time taken would be
t = 200/7.47
t = 26.7 s
Answer:
313.6 m downward
Explanation:
The distance covered by the bullet along the vertical direction can be calculated by using the equation of motion of a projectile along the y-axis.
In fact, we have:
where
y(t) is the vertical position of the projectile at time t
h is the initial height of the projectile
is the initial vertical velocity of the projectile, which is zero since the bullet is fired horizontally
t is the time
a = g = -9.8 m/s^2 is the acceleration due to gravity
We can rewrite the equation as
where the term on the left, , represents the vertical displacement of the bullet. Substituting numbers and t = 8 s, we find
So the bullet has travelled 313.6 m downward.
Lightning is an electric current. Within a thundercloud way up in the sky, many small bits of ice (frozen raindrops) bump into each other as they move around in the air. All of those collisions create an electric charge. After a while, the whole cloud fills up with electrical charger