Hello :))
Mass is dependent on the inertia of an object:))
Hope this helps
Answer:
<em>The bullet was 0.52 seconds in the air.</em>
Explanation:
<u>Horizontal Motion
</u>
It occurs when an object is thrown horizontally with a speed v from a height h.
The object describes a curved path ruled exclusively by gravity until it hits the ground.
To calculate the time the object takes to hit the ground, we use the following equation:

Note it doesn't depend on the initial velocity but on the height.
The bullet is fired horizontally at h=1.3 m, thus:


t = 0.52 s
The bullet was 0.52 seconds in the air.
The time taken by the swimmer was 1 hour.
Why?
Since the swimmer is maintaining an angle of 150° while he was swimming, there were two components of the speed (horizontal and vertical). If we want to calculate the time taken by him to cross the river, we need to calculate the vertical speed and consider that the flow's speed is compensated by his horizontal speed.
We can calculate both components of the speed using the following formula:

Now, calculating we have:

Therefore, we have that the horizontal speed is compesating the flow's speed while his vertical speed is used to cross the river which is 1 Km wide.
Hence, we have that the tame taken is:

Have a nice day!
Gravitational force is the result of the earth pulling down on the book, so the normal force is best described as the earth or more accurately the table pushing up on the book