Question

Which can change the direction of a downward input force into an upward output force?

A.
screw

B.
crowbar

C.
can opener

D.
ax blade

Answer 1

@paki B?

Answer 2

yup .. correct ;-)

Answer 3

Can you help me with a few more?

Answer 4

Which describes the relationship between potential and kinetic energy of a ball thrown up in the air as it falls back to the ground?

A.
Gravitational potential energy increases; kinetic energy increases.

B.
Kinetic energy equals gravitational potential energy.

C.
The mass of the ball is required to answer this.

D.
Kinetic energy increases; gravitational potential energy decreases.

Answer 5

A?

Answer 6

what do you think?

Answer 7

why!?

Answer 8

can you justify?

Answer 9

or D?

Answer 10

Its important u tell me.. what you are thinking.. so I can help u!

Answer 11

Because the gravity is pulling it back to earth so the gravitational pull is greater

Answer 12

erm.. gravitational pull remains the same.. the famous 9.8.. as long as you are close to earth.. And a ball thrown up is close to earth..

Answer 13

So would it be B then?

Answer 14

No C because we do not know the size of the ball so we do not know how much the gravitational potential energy would be.

Answer 15

Gravitational potential energy depends on height..
U = mgh

Kinetic energy depends on Speed.. K = 0.5 mv^2

Answer 16

You are right that we dunno exactly how much the PE is unless you know the mass... but we can surely answer whether the K and U are increasing or decreasing

Answer 17

So it is C because we do not know the mass of the ball?

Answer 18

we don't need the mass of the ball.. to figure out if its INCREASING OR DECREASING!

Answer 19

Because it is falling back to earth the kinectic energy is greater

Answer 20

its not greater.. it is increasing.. I hope thats what you meant!

Answer 21

Yes sorry

Answer 22

and the height is decreasing so what is happening to the P.E ?

Answer 23

increasing?

Answer 24

Sorry im not good at Energy

Answer 25

No it decreases!

Answer 26

It is D

Answer 27

yes.. sorry.. i forgot to check back :P

Answer 28

Which label identifies the statement: "Energy cannot be created or destroyed, but it can be converted or changed into different forms.

A.
the law of energy equilibrium

B.
the law of conservation of matter

C.
the law of conservation of energy

D.
the law of energy transformation <------
@Mashy

Answer 29

there is no law of energy transformation :P

Answer 30

Then C

Answer 31

I told you im not good at Energy

Answer 32

correct!!!!

Answer 33

conservation of energy :)

Answer 34

kinetic energy increases, gravitation pot deceases :)

Answer 35

and crowbar yes :)