The density value 3.291 g/ml (gram / milliliter) in words is "three point two nine one g/ml (gram / milliliter)".
=)
If the desk doesn't move, then it's not accelerating.
If it's not accelerating, then the net force on it is zero.
If the net force on it is zero, then any forces on it are balanced.
If there are only two forces on it and they're balanced, then they have equal strengths, and they point in opposite directions.
So the friction on the desk must be equal to your<em> 245N</em> .
Answer:
20m/s due east
Explanation:
Given parameters:
Displacement eastward = 200m
Time = 10s
Unknown:
Velocity = ?
Solution:
Velocity is the displacement divided by time;
Velocity = 
Velocity = 
= 20m/s due east
The only correct statement on that list is <em>choice-C</em>: If a positively charged rod is brought close to a positively charged object, the two objects will repel.
-- Gravity makes a falling object fall 9.8 m/s faster every second.
-- So, it reaches the speed of 30 m/s in (30/9.8) = 3.06 seconds after it's dropped.
-- The distance an object falls from rest is D = 1/2 (acceleration) (time)²
D = 1/2 (9.8 m/s²) (3.06 sec)²
D = (4.9 m/s²) (9.37 sec²)
<em>D = 45.8 meters</em>
Notice that we don't care how high the building is. The problem works just as long as the object can reach 30 m/s before it hits the ground. That turns out to be anything higher than 45.8 meters for the drop . . . maybe something like 13 floors or more.
Now I'll go a little farther for you ! Writing the last paragraph made me a little curious and uncomfortable. So I went and looked up the world's tallest buildings . . . and I found out that this problem could never happen !
The tallest building in the world now is the Burj Khalifa, in Dubai. It has 163 floors, and it's 828 meters high ! That's 2,717 feet. It's gonna be a long time before there's a building that's 1125 meters tall, like this problem says. That's close to 3700 feet . . . I've had flying lessons where I wasn't that far off the ground !
