# Math Help - Calculus heavy physics problem

1. ## Calculus heavy physics problem

A 5.00 crate is suspended from the end of a short vertical rope of negligible mass. An upward force is applied to the end of the rope, and the height of the crate above its initial position is given by +(0.61 )

What is the magnitude of the force when 3.60 ?

Alright, I have done about 20 physics problems that are due next week, and this is the last one. It is very heavy on calculus, which i am not good at. In fact, I don't even really know where to start on this one. Thanks for the help.

2. ## Re: Calculus heavy physics problem

Originally Posted by CrusaderKing1
A 5.00 crate is suspended from the end of a short vertical rope of negligible mass. An upward force is applied to the end of the rope, and the height of the crate above its initial position is given by +(0.61 )

What is the magnitude of the force when 3.60 ?

Alright, I have done about 20 physics problems that are due next week, and this is the last one. It is very heavy on calculus, which i am not good at. In fact, I don't even really know where to start on this one. Thanks for the help.
$y(t) = 2.80t + 0.61t^3$

surely you know how to take derivatives of polynomial expressions ...

$a(t) = y''(t)$

$F(t) = m \cdot a(t)$

3. ## Re: Calculus heavy physics problem

Originally Posted by skeeter
$y(t) = 2.80t + 0.61t^3$

surely you know how to take derivatives of polynomial expressions ...

$a(t) = y''(t)$

$F(t) = m \cdot a(t)$
Yes, If the question said use the derivative, and then find F(t), I would have understood it. I am very bad at starting problems!

Ok, I did derive the function and received 20.6848 for acceleration, with then multiplied by 5.00 kg = 103.424

Would the units be in N? Probably N right? Yes, I'm not very good at this yet.

Thanks for your help! Much appreciated.

4. ## Re: Calculus heavy physics problem

Originally Posted by CrusaderKing1
Yes, If the question said use the derivative, and then find F(t), I would have understood it. I am very bad at starting problems!

Ok, I did derive the function and received 20.6848 for acceleration, with then multiplied by 5.00 kg = 103.424

Would the units be in N? Probably N right? Yes, I'm not very good at this yet.

Thanks for your help! Much appreciated.
incorrect

$a(6) = 21.96 \, m/s^2$ ... recheck your calculations

at this level of calculus-based physics, you are expected to know the relationship between position, velocity, and acceleration ...

$v(t) = y'(t)$

$a(t) = v'(t) = y''(t)$

5. ## Re: Calculus heavy physics problem

Originally Posted by skeeter
incorrect

$a(6) = 21.96 \, m/s^2$ ... recheck your calculations

at this level of calculus-based physics, you are expected to know the relationship between position, velocity, and acceleration ...

$v(t) = y'(t)$

$a(t) = v'(t) = y''(t)$
65.88 N

I didn't realize that I need to derive the function twice.

I have calculus and physics this semester, and had only high school trig. before 5 weeks ago.

The value is definitely right, but the program(masteringphysics) won't accept "N" as the correct units.

would kg*m/s2 work?

Thanks.

6. ## Re: Calculus heavy physics problem

Originally Posted by CrusaderKing1
65.88 N

I didn't realize that I need to derive the function twice.

I have calculus and physics this semester, and had only high school trig. before 5 weeks ago.

The value is definitely right, but the program(masteringphysics) won't accept "N" as the correct units.

would kg*m/s2 work?
Thanks.
Not being familiar with what the "machine" wants, I can't really say ... it's worth a shot.

7. ## Re: Calculus heavy physics problem

Originally Posted by skeeter
Not being familiar with what the "machine" wants, I can't really say ... it's worth a shot.
yes, I guess so.