Kinematics and magnitude problem

[nightlaei71]

What is the magnitude of velocity of an object after free falling from rest after 3 minutes?
(A) 9.8 m/s (D) 180 m/s
(B) 32 m/s (E) 1800 m/s
(C) 87 m/s

I think the answer is 1800 m/s but I'm not sure how to arrive at it.

 

[arildno]

Well, what equation would you use?

 

[nightlaei71]

I have no idea, the equations that we studied in this chapter don't seem to work with this problem.

 

[arildno]

What does free fall mean?

 

[nightlaei71]

it's falling without a drag-producing device like a parachute

 

[Dooga Blackrazor]

Have you tried transfering your minutes into seconds before putting everything into your formula?

 

[nightlaei71]

I don't even know what formula to use. I'm in an AP class that my teacher doesn't show up to. He just assigns us homework and shows us videos. The book isn't much help at all so I'm completely lost.

 

[Dooga Blackrazor]

If those are the only questions you have I'd just ask someone before you have to return the assignment. The formula is probably fairly straight forward and easily explainable. Afterwards you can just do the other questions quickly.

If your book has the answer in the back I might be able to determine the formula.

 

[nightlaei71]

no answers...

 

[Doc Al]

Hint: What is the meaning of "acceleration due to gravity"?

 

[nightlaei71]

the pull of gravity causes objects to accelerate towards the ground... that doesn't really help me

 

[Doc Al]

It would help you if you know what acceleration means. What's the definition of acceleration?

And what is the acceleration due to gravity?

 

[nightlaei71]

You're right, it would help, but like I said, I really don't know. : /

 

[Doc Al]

Acceleration is the rate of change of velocity; the acceleration due to gravity is 9.8 $m/s^2$.

 

[vladimir69]

hi,
you could try using this equation
$$v=u+at$$ where v is the final velocity and u is the initial velocity
t is the time in seconds
a is acceleration
in your case a=9.8m/s^2
t=3*60 seconds = 180 seconds
now pop in the numbers and out will pop the answer

 

[aviv87]

Actually, considering the options he was given, I'd say in his course the acceleration due to gravity is used as $$10\ m/s^2$$

 

[nightlaei71]

Actually, considering the options he was given, I'd say in his course the acceleration due to gravity is used as $$10\ m/s^2$$

"he"? I'd hope not...

 

[Raza]

Question:
What is the magnitude of velocity of an object after free falling from rest after 3 minutes?

Solution:
Time:180s <----(3)(60) to convert to seconds
Acceleration:$$9.8m/s^2$$ <---- Gravitational Force on Earth
D=(A)(T)
D=(9.8)(180s)

Answer:
1764m

I might be wrong

*Edit: When I read my post again, I got confused, are you trying to find out the distance?

 

[nelufar]

Question:
What is the magnitude of velocity of an object after free falling from rest after 3 minutes?

Solution:
Time:180s <----(3)(60) to convert to seconds
Acceleration:$$9.8m/s^2$$ <---- Gravitational Force on Earth
D=(A)(T)
D=(9.8)(180s)

Answer:
1764m

I might be wrong

*Edit: When I read my post again, I got confused, are you trying to find out the distance?

Here since the object is falling freely from rest, initial velocity(u) is zero. So now you have to find the final velocity(v). Use v = u + at, where a= $$9.8m/s^2$$. So your answer is right. If you want to calculate distance, then use $$s = ut + {1 \over 2}a t^2$$.

 

[tony873004]

A car goes from 0 to 60 in 8 seconds. If it could keep up this acceleration, how fast would it be going in 16 seconds?

Do your problem the same way.