<span>The question says, what drives surface current. The correct option is A, that is wind. There are two different current system in the ocean, they are deep circulation and surface circulation. Surface current is majorly driven by the wind. The wind is capable of moving the top 400 meters of the ocean, thereby creating ocean surface current. The pattern of the surface current is determined by the direction of the wind, forces from the earth rotation and the position of the landform that interact with the current.</span>
Imagine a ball is moving on the following horizontal line.
. . . . . . . . . . . . . . . . . . . O. . . . . . . . . . . . . . . . . .
Take right as positive. O is the starting point of the ball. Denote the ball by o.
. . . . . . . . . . . . . . . . . . . O. . . . . . . ... . . o . . . . . .
Assume the ball is moving to the right. It has positive displacement since it is on the right of O, and positive velocity since its positive displacement is increasing.
.ñ
. . . . . . . . . . . . . . . . . . . O. . . . o . . . . . . . . . . . . .
Now the ball is returning to O. It still has positive displacement since its current position is still on the right of O. However, its velocity is negative since its positive displacement is decreasing and the direction of the velocity vector points left, which is the negative side.
By now you should be able to come up with a scenario where the ball has negative displacement and positive velocity.
You can observe the same phenomenon in daily life. Say, as a stretched spring bounces to its starting position, if we let the returning direction be positive, the string has negative displacement since it is on the negative direction, but has positive velocity. Bungee jump can also used to illustrate the phenomenon.
Answer: a. -720m/s^2
b. Yes, airbags will deploy
Explanation:
The formula for acceleration is:
= (Final velocity - Initial velocity)/Time
Final velocity = 0m/s
Initial velocity = 36m/s
Time taken = 0.05s
= (Final velocity - Initial velocity)/Time
= (0 - 36)/0.05
= -36/0.05
= -720m/s^2.
Since it's negative, it shows that there was a deceleration.
2. Yes the airbag will deploy since the acceleration gotten is more than -600 m/s^2.
Answer:
The principle of momentum conservation states that if there no external force the total momentum of the system before and after the collision is conserved.
Since momentum is a vector, we should investigate the directions and magnitudes of initial and final momentum.

If the first ball hits the second ball with an angle, we should separate the x- and y-components of the momentum (or velocity), and apply conservation of momentum separately on x- and y-directions.