Answer:
Explanation:
for vertical movement , time to reach the top = time to reach the hand = 2.5 s
v = u - gt
At the top , v = 0 , time t = 2.5 s
0 = u - g x 2.5
u = 2.5 x 9.8 = 24.5 m /s
velocity of throw = 24.5 m /s
So , when it passes the hand on its way down , it will have velocity equal to 24.5 m /s and it will accelerate downwards . Let its velocity down by 22 m be v
v² = u² + 2 g s
= 24.5² + 2 x 9.8 x 22
= 600.25 + 431.2
= 1031.45
v = 32.11 m /s .
There is a correct answer to this question, and then there is the one they want you to choose. Which one should I give you first ?
Let's start with the correct answer:
The force of gravity on any object is
(mass of the object)
times
(acceleration of gravity on the planet where the object is) .
The acceleration of gravity on Earth is about 9.8 m/s²,
so the force of gravity on this object is
(4000 kg/m³) x (0.9 m³) x (9.8 m/s²)
= (3,600 kg) x (9.8 m/s²)
= 35,280 kg-m/s² = 35,280 Newtons.
That's the force of gravity attracting this block and the Earth
toward each other. It makes no difference whether the block
is in your bedroom closet, in the back yard under a pile of mulch,
inside a steel safe resting on a bed of styrofoam peanuts and
slivered almonds, or underwater in the neighbor's pool.
That's the force of gravity on this block, and it's the correct answer
to the question.
It's not one of the choices, though. That's because the question
is poorly written. The person who wrote the question is unclear on
the concepts, and the more you work with the question, the more
unclear and confused YOU'LL become.
When the block is in water, the force of gravity on it doesn't change.
BUT ... there's ANOTHER force on it ... the buoyant force ... acting
upward on it, and canceling part of the force of gravity.
The buoyant force is the weight of the displaced water.
The displaced water is the water that has to get out of the way
when you drop the block in, so the volume of displaced water
is the volume of the block.
-- The volume of the block is (0.9 m³).
-- The density of water is 1000 kg/m³, so the mass of 0.9 m³ of water
is 900 kg.
-- The weight of 900 kg of water is (mass) x (gravity)
= (900 kg) x (9.8 m/s²)
= 8,820 Newtons.
When the block is in water, it feels like it's that much LIGHTER,
because that's the force of the water pushing UP on the block.
It's the same reason why your big brother seems so light in the
pool that you can pick him up and carry him.
So how heavy does this block FEEL in water ?
The force of gravity pulling down on it: 35,280 newtons
The force of water pushing up on it: 8,820 newtons
How heavy the block feels (the difference) 26,460 newtons
The question is written so poorly that even THIS number
is not one of the choices.
Again, the thing to realize is that being in the water does NOT
change the force of gravity on anything. It only creates another
force, that acts against gravity.
Just like . . . When you walk up some stairs, how does it happen
that you suddenly move upward, opposite to gravity. Does the force
of gravity acting on you change ? No ! But you use your leg muscles
to create another force in the opposite direction, that works against
gravity, and makes you seem so light that you can actually move up,
opposite to gravity.
Answer:
To create this comic strip you can use a narration describing each step and illustrate each one with one image or drawing.
Creating a comic strip involves using images and short texts to explain a specific idea or phenomenon. In the case of the process for a meteor to enter Earth you can use the following ideas.
A meteoroid approaches the Earth at high speed and draw a meteor traveling near to different planets and approaching Earth.
What is that? and draw the Earth wondering who or what is approaching.
The meteoroid enters the atmosphere of the Earth and becomes a meteor and draw the rocky body burning
The rocky body crashes with the surface becoming a meteorite and draw the zone where the meteorite crashed.
Explanation:
<h3><u>Technology used by astronomers to look for life on other plants:</u></h3>
- Space-based Hubble and Spitzer telescopes and Green Bank telescopes are used.
- Many new satellites are launched to trace earth like planets. Even the telescopes are carried by spacecrafts.
- Astronomers are using Allen Telescope Array that comprises 42 radio antennas to get hold of signals over a wide range of radio frequencies that are tuned to listen to the regions nearer to the red dwarf star constellations.
- Scientists needed telescopes that are capable of detecting planets like Earth in our planet’s neighborhood and see if any biological signatures connected to any microbial or other intelligent life can be found.
- Radio signals are also being used to detect if the outside world has something to communicate so that they can be detected.
