How much gravitational potential energy does the block have
when it gets to the top of the ramp ?
(weight) x (height) = (15 N) x (0.2 m) = 3 Joules .
If there were no friction, you would only need to do 3 Joules of work
to lift the block from the bottom to the top.
But the question says you actually have to do 4 Joules of work
to get the job done.
Friction stole one of your Joules along the way.
Choice-4 is not the correct one.
Choice-1 is the correct one.
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Notice that the mass of the block is NOT 15 kg , and you
don't have to worry about gravity to answer this question.
The formula for potential energy is (m)·(g)·(h) .
But (m·g) is just the WEIGHT, and the formula
is actually (weight)·(height).
The question GIVES us the weight of the block . . . 15 N .
So the potential energy at the top is just (15N)·(0.2m) = 3 Joules.
Mechanical waves need material stuff to travel through.
They cannot travel through vacuum.
That's why we can't hear the explosions on the sun.
That's also why astronauts standing on the moon or working outside the Space Station have to use radio to talk to each other, even if they're only a few inches apart. There's no air between them, or any other material stuff. So sound can't travel between them.
Answer:
Explanation:
if t=3.6s and initial velocity, v0, is -5m/s
if t=3.6s and the initial displacement, s0, is -8m:
The answer would be 0.21 i believe if you use something we called F/Ma in grade school
