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MrRissso [65]
3 years ago
7

As you push a cereal box across a tabletop, the sliding friction acting on the cereal box_____. a.) acts in the direction of mot

ion. b.) equals the weight of the box. c.) is usually greater than static friction. d.) acts in the direction opposite of motion. 2.) Projectile motion is caused by____________. a.) the downward force of gravity. b.) the initial forward velocity. c.) a final vertical velocity d.) the downward force of gravity and an initial forward velocity.
Physics
2 answers:
Kamila [148]3 years ago
6 0

1: d) acts in the direction opposite of motion

Explanation:

Sliding friction is a force that is exerted when an object is sliding along a surface. Due to the surfaces are never perfectly smooth, the collisions between the molecules at the edges of the object and the surface "slow down" the motion of the object. Because of this, sliding friction acts in the direction opposite of motion.

2: d.) the downward force of gravity and an initial forward velocity.

A projectile motion is a motion that consists of two independent motions:

- A horizontal motion at constant velocity

- A vertical accelerated motion with constant acceleration (g, gravitational acceleration, due to the force of gravity which acts downwards)

Therefore, projectile motion is caused by the downward force of gravity and an initial forward velocity.


evablogger [386]3 years ago
5 0
1. As you push a cereal box across a tabletop, the sliding friction acting on the cereal box_____. 
<span> d.) acts in the direction opposite of motion. </span>
2.) Projectile motion is caused by____________.
d.) the downward force of gravity and an initial forward velocity.
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Is (2, 2) a solution of y &lt; 4x-6<br> Help
vesna_86 [32]

Answer:

B) No.

Explanation:

Okay,so,

this is equation is y=mx +b

mx represents the slope

and b represents the y-intercept

in order to figure this out you need to plot the y-intercept first

that makes its (0,-6) because the 6 is negative in the equation

4x is also equal to 4/1 since we dont know what x is

we have to do rise over run for this

you go up 4 spots on the y intercept from -6 because 4 is positive

then you go to the right 1 time because 1 is positive.

this leaves you at (1,-2)

so, (2,2) is NOT a solution

7 0
3 years ago
Sketch a reaction progress curve for a reaction that has an activation energy of 22 kj and the total energy change is -103kj.
crimeas [40]

Answer:

Do find the answer in the attachment herein.

Explanation:

From the attached diagram:

I. Activation energy = Activated complex - ∆H(reactants)

Activation energy = 162-140 = 22Kj.

II. ∆H(reaction) = ∆H(products) - ∆H(reactants)

∆H(reaction) = 37 - 140 = -103Kj.

8 0
4 years ago
A ball is rolling across the floor at a constant speed. What will happen to the ball if it is exposed
ELEN [110]
I think it’s speed will increase, if I understood it correctly
7 0
3 years ago
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Why would we expect protogalactic clouds with relatively high density to form an elliptical galaxy rather than a spiral galaxy?
Svetlanka [38]

The higher density allows the protogalactic clouds to cool faster and form an elliptical galaxy rather than a spiral galaxy.

In physical cosmology, a protogalaxy or protogalactic cloud , which could also be called a "primeval galaxy", is a cloud of gas which is forming into a galaxy. It is believed that the rate of star formation during this period of galactic evolution will determine whether a galaxy is a spiral or elliptical galaxy; a slower star formation tends to produce a spiral galaxy. The smaller clumps of gas in a protogalaxy form into stars.

Composition

Since there had been no previous star formation to create other elements, protogalaxies would have been made up almost entirely of hydrogen and helium. The hydrogen would bond to form H2 molecules, with some exceptions. This would change as star formation began and produced more elements through the process of nuclear fusion.

Mechanics

Once a protogalaxy begins to form, all particles bound by its gravity begin to free fall towards it. The time taken for this free-fall to conclude can be approximated using the free-fall equations. Most galaxies have completed this free-fall stage to become stable elliptical or disk galaxies, the disks taking longer to fully form. The formation of galaxy clusters takes much longer and is still in progress now.

This stage is also where galaxies acquire most of their angular momentum. A protogalaxy acquires this due to gravitational influence from neighbouring dense clumps in the early universe, and the further the gas is away from the centre, the more spin it gets.

Learn more about protogalactic clouds here : brainly.com/question/28166070

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7 0
2 years ago
A high-jumper, having just cleared the bar, lands on an air mattress and comes to rest. Had she landed directly on the hard grou
Hoochie [10]

Answer:

e. the air mattress exerts the same impulse, but a smaller net avg force, on the high-jumper than hard-ground.

Explanation:

This is according to the Newton's second law and energy conservation that the force exerted by the hard-ground is more than the force exerted by the mattress.

The hard ground stops the moving mass by its sudden reaction in the opposite direction of impact force whereas the mattress takes a longer time to stop the motion of same mass in a longer time leading to lesser average reaction force.

<u>Mathematical expression for the Newton's second law of motion is given as:</u>

F=\frac{dp}{dt} ............................................(1)

where:

dp = change in momentum

dt = time taken to change the momentum

We know, momentum:

p=m.v

Now, equation (1) becomes:

F=\frac{d(m.v)}{dt}

<em>∵mass is constant at speeds v << c (speed of light)</em>

\therefore F=m.\frac{dv}{dt}

and, \frac{dv}{dt} =a

where: a = acceleration

\Rightarrow F=m.a

also

F\propto \frac{1}{dt}

so, more the time, lesser the force.

<em>& </em><u><em>Impulse:</em></u>

I=F.dt

I=m.a.dt

I=m.\frac{dv}{dt}.dt

I=m.dv=dp

∵Initial velocity and final velocity(=0), of a certain mass is same irrespective of the stopping method.

So, the impulse in both the cases will be same.

4 0
3 years ago
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