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Luden [163]
3 years ago
15

Suppose the truck that’s transporting the box In Example 6.10 (p. 150) is driving at a constant speed and then brakes and slows

at a constant acceleration. While coming to a stop, the driver looks in the rear-view mirror and notices that the box is not slipping. In what direction is the frictional force acting on the box?
Physics
1 answer:
Scorpion4ik [409]3 years ago
5 0

Answer:

Friction acts in the opposite direction to the motion of the truck and box.

Explanation:

Let's first review the problem.

A moving truck applies the brakes, and a box on it does not slip.

Now when the truck is applying brakes, only it itself is being slowed down. Since the box is slowing down with the truck, we can conclude that it is friction that slows it down.

The box in the question tries to maintains its velocity forward when the brakes are applied. We can think of this as the box exerting a positive force relative to the truck when the brakes are applied. When we imagine this, we can also figure out where the static friction will act to stop this positive force. Friction will act in the negative direction. Or in other words, friction will act in the opposite direction to the motion of the truck and box. This explains why the box slows down with the truck, as friction acts to stop its motion.

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8 0
3 years ago
Can you explain that gravity pulls us to the Earth & can you calculate weight from masses on both on Earth and other planets
schepotkina [342]
I don't actually understand what your question is, but I'll dance around the subject
for a while, and hope that you get something out of it.

-- The effect of gravity is:  There's a <em>pair</em> of forces, <em>in both directions</em>, between
every two masses.

-- The strength of the force depends on the <em>product</em> of the masses, so it doesn't matter whether there's a big one and a small one, or whether they're nearly equal. 
It's the product that counts.  Bigger product ==> stronger force, in direct proportion.

-- The strength of the forces also depends on the distance between the objects' centers.  More distance => weaker force.  Actually, (more distance)² ==> weaker force.

-- The forces are <em>equal in both directions</em>.  Your weight on Earth is exactly equal to
the Earth's weight on you.  You can prove that.  Turn your bathroom scale face down
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If you put a little mirror down under the numbers, you'll see that it's the same as
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-- When you (or a ball) are up on the roof and step off, the force of gravity that pulls
you (or the ball) toward the Earth causes you (or the ball) to accelerate (fall) toward the Earth. 
Also, the force that attracts the Earth toward you (or the ball) causes the Earth to accelerate (fall) toward you (or the ball).
The forces are equal.  But since the Earth has more mass than you have, you accelerate toward the Earth faster than the Earth accelerates toward you.

--  This works exactly the same for every pair of masses in the universe.  Gravity
is everywhere.  You can't turn it off, and you can't shield anything from it.

-- Sometimes you'll hear about some mysterious way to "defy gravity".  It's not possible to 'defy' gravity, but since we know that it's there, we can work with it.
If we want to move something in the opposite direction from where gravity is pulling it, all we need to do is provide a force in that direction that's stronger than the force of gravity.
I know that sounds complicated, so here are a few examples of how we do it:
-- use arm-muscle force to pick a book UP off the table
-- use leg-muscle force to move your whole body UP the stairs
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-- The weight of 1 kilogram of mass on or near the Earth is 9.8 newtons.  (That's
about 2.205 pounds).  The same kilogram of mass has different weights on other planets. Wherever it is, we only know one of the masses ... the kilogram.  In order
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I hope I told you something that you were actually looking for.
7 0
3 years ago
Is Mercury a heavier element than tin
Kryger [21]
Yes because mercury has more protons and electrons that tin. (30 more)
4 0
3 years ago
Write 200m and 2 ×10^4m in km<br><br><br>write 5000ms and 5×10^7ms in seconds
WINSTONCH [101]

Answer:

a) 20.2 kilometers

b)50 005 seconds

Explanation:

5 0
3 years ago
I have a hot air balloon that has 18.0 g helium gas inside of it. if the pressure is 2.00 atm and the temperature is 297k, what
Anastaziya [24]

M = molar mass of the helium gas = 4.0 g/mol

m = mass of the gas given = 18.0 g

n = number of moles of the gas

number of moles of the gas is given as

n = m/M

n = 18.0/4.0

n = 4.5 moles

P = pressure = 2.00 atm = 2.00 x 101325 Pa = 202650 Pa

V = Volume of balloon = ?

T = temperature = 297 K

R = universal gas constant = 8.314

Using the ideal gas equation

P V = n R T

(202650) V = (4.5) (8.314) (297)

V = 0.055 m³

4 0
3 years ago
Read 2 more answers
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