This is my 4th time taking Physics. It is also the last class I need to be done with my degree. I can't understand it. I am getting very discouraged.

Right now the question I have is I think a simple one I just can't think of it. How do you find the height of a table when all you have is a physics book fell off the table with a speed of 1.10m/s and it took 0.350s to hit the floor.

divide.

how fast was it falling? How long did it take to fall?

distance = rate times time.
distance (miles) = rate (miles/hour) times time (hours).
works same if you use meters and meters per second.

after 4 years in physics you do not remember d=rt?


This is my 4th time taking Physics. It is also the last class I need to be done with my degree. I can't understand it. I am getting very discouraged.

Right now the question I have is I think a simple one i just can't think of it. How do you find the height of a table when all you have is a physics book fell off the table with a speed of 1.10m/s and it took 0.350s to hit the floor.

Its simply proportionality

As it says: 1.10 metre per second
In one second, it makes 1.10 metre
Therefore in 0.350 seconds, it makes : 1.10 * 0.350

An object that falls under gravity does not fall at a constant speed, but rather accelerates as it falls. When you say that the book fell with a speed of 1.10 m/s do you mean that it was given an initial downward "push" of 1.10 m/s, or do you mean that when the book hit the floor it was traveling at 1.10 m/s? If we assume the latter, then the distance an object travels is given by:


v_f^2 - v_i^2= 2ad


In this problem you know that v_i (the initial velocity) is 0, and v_f (its final velocity) is 1.10 ms, and a = g = 9.8 m/s^2. So you simply plug and chug to find the distance d.

Actually, the more I think about this... with the data that you are given there is a second way to solve this.

The fact that the book hits the floor after 0.35s tells you that the distance it travelled is:


d = \frac 1 2 a t^2 = \frac 1 2 (9.8m/s^2) \cdot (1.1 s)^2


The answer you get from this method does not agree with the solution from my previous post. Which means either (a) I am misunderstanding the question, or (b) the question was not properly written. So Jenimo - please repost with the problem as originally written - don't try to paraphrase it. Thanks.

Hey, you got a point there and I understand the difficulties now. I didn't pay attention to the acceleration due to gravity. Shame on me! Anyway, your second post seems more relevant to me.