Question

A pendulum is used in a large clock. The pendulum has a mass of 2 kg. If the pendulum is moving at a speed of 4.1 m/s when it reaches the lowest point on its path, what is the maximum height of the pendulum?

A. 0.86 m
B. 0.63 m
C. 0.51 m
D. 0.75 m

Answer 1

how far along are you in physics? have you learned about oscillatory motion? or have you only learned about momentum?

Answer 2

i don't really know that much..

Answer 3

do you know what simple harmonic motion is?

Answer 4

@LastDayWork I'm actually not sure how to approach this problem. Pendulums are typically part of oscillatory motion, but as of right now @marius.roine has only asked me about collisions which is part of linear momentum. Because of that I've considered using an angular momentum approach but i'm stuck

Answer 5

Well, I can't see any correlation with collision here. Simply conserving the mechanical energy will give the answer.

Answer 6

\[E_i = E_f\]
but are you referring to kinetic or potential energy?

Answer 7

Only mass and velocity are known, that's not much to go by
Then again, I'm a bit rusty in the energy approach in mechanics

Answer 8

(1/2)mv^2 = mgh

We can find 'h' from the above equation..
We could also use angular approach; but I prefer doing things in a lazy way ;)

Answer 9

then what's the point of knowing mass if it just cancels out? or is that for the angular approach I suggested?

Answer 10

Mass will cancel out in the angular approach too...try it :)

Answer 11

I actually don't even know how to do it that way. that's why i asked you for help :(
it's kinda sad really, I know it's possible, I don't know the how

Answer 12

Only mg can give torque as Tension would always be directed towards the axis of rotation.

The approach would be a little messy as the component of mg, which gives torque, will be changing with time.

Answer 13

(1/2) m v^2 = m g h sure is a clean solution method

Answer 14

what will the answer be then @LastDayWork @roadjester

Answer 15

Use -
(1/2)mv^2 = mgh

and find 'h'

Answer 16

so 1/2 x 2 x 4.1^2 = 16.81 @LastDayWork

Answer 17

Yea..now equate the expression to RHS..

Answer 18

how can I do that

Answer 19

Do you know how to solve equations ??

Answer 20

yes, but not this one

Answer 21

Use -
h = (1/2) v^2 /g

Answer 22

where g is the acceleration due to gravity.

Answer 23

so it wil be A