In which of the following situations has the energy of the object been increased?

A. A hammer thrower spins around while preparing to release the hammer.

B. A horse moves horizontally while a circus performer jumps vertically on its back.

C. A boy pushes a lawn mower forward by pushing at a downward angle on the handle.

D. A soldier runs forward, while holding a rifle above his head.

***I think it's choice A, but I'm not 100% sure!! is that correct? :/ Thank you!! :)

Question

In which of the following situations has the energy of the object been increased?

A.       A hammer thrower spins around while preparing to release the hammer.

B.       A horse moves horizontally while a circus performer jumps vertically on its back.

C.       A boy pushes a lawn mower forward by pushing at a downward angle on the handle.

D.       A soldier runs forward, while holding a rifle above his head.

***I think it's choice A, but I'm not 100% sure!! is that correct? :/ Thank you!! :)

amistre64 · Answer

that does seem most appropriate,  the hammer has to store up energy in order to move after being released.

anonymous · Answer

ahh yay!! :) thank you!!

and also for this one, the answer should be "work," right? 

Which of the following is a scalar quantity?

parallel component of force, perpendicular component of force, displacement, or work
 
but I'm not sure if I am confusing it? :/

amistre64 · Answer

a scalar quantity has no direction ... its length, weight, temperature, brightness, something measured ....

amistre64 · Answer

work is a vector product ...  Force is a vector

amistre64 · Answer

not sure which of those are scalar in general ....

anonymous · Answer

ohh okay thank you!!! :D

amistre64 · Answer

define displacement for me

anonymous · Answer

it's like how far out of place something is, right?

amistre64 · Answer

displacement is a vector  at least it can be represented as a vector

astrophysics · Answer

Displacement is a vector I guess since you don't know transformations and such you can think of it as it has a magnitude and direction.

anonymous · Answer

ohh okie!! thank you!! :D

anonymous · Answer

@amistre64 @Astrophysics  :)

astrophysics · Answer

Scalar quantity is anything with magnitude, where vector is anything with magnitude AND direction

amistre64 · Answer

the parallel and perp stuff i wouldnt know about off hand

anonymous · Answer

okay, i will (try to!!) remember that :P

astrophysics · Answer

Forces are vectors, but the magnitude of a force can be related to scalars, kind of wordy. But, the forces here are vectors. I find if it interesting they would ask you such a question so early, work is a scalar quantity as we are dealing with dot products of vector quantity, which gives a scalar. Physics is weird man!