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Vedmedyk [2.9K]
3 years ago
13

a librarian pushes a 35kg box of books across the library floor. if the carpet resists with a friction force of 91N, what force

must be applied by the librarian to accelerate the box at a rate of 0.50m/s​
Physics
1 answer:
MArishka [77]3 years ago
3 0

Answer:

F = 108.5 [N]

Explanation:

To solve this type of problem we must use Newton's second law, which tells us that the sum of forces must be equal to the product of mass by acceleration.

ΣF = m*a

where:

ΣF = sum of forces [N]

m = mass = 35 [kg]

a = acceleration = 0.5 [m/s²]

f = friction force [N]

F - f = m*a

F - 91 = (35*.5)

F = 91 + 17.5

F = 108.5 [N]

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A plane travels down a runway 2750 m before it lifts off at an angle of 37 degrees from the horizontal. The plane has traveled 1
ss7ja [257]

Answer: 4.236km

Explanation:

Let's define the point (x, y) as:

x = horizontal distance moved.

y = vertical distance moved.

If the plane starts in the point (0, 0) then:

"A plane travels down a runway 2750 m before it lifts off..."

At this time, the position will be:

P = (0 + 2750m, 0) = (2750m, 0).

"it lifts off at an angle of 37 degrees from the horizontal. The plane has traveled 1.8 km since its wheels left the ground."

In this case, as the angle is measured from the horizontal, the components will be:

x = 1.8km*cos(37°) = 1.438km

y = 1.8km*sin(37°) =  1.083 km

Then the new position is:

P = (2750m + 1.438 km, 0 + 1.083 km)

Let's write it using the same units for all the quantities:

we know that

1km = 1000m

Then:

2750m = (2750/1000) km = 2.750 km.

Then we can write the new position as:

P = (2.750 km + 1.438km, 1.083km) = (4.188km, 1.083km)

Now, we define the displacement as the distance between the final position and the initial position.

The distance between two points (a, b) and (c, d) is:

D = √( (a  c)^2 + (b - d)^2)

In this case the points are:

(0, 0) for the initial position

(4.188km, 1.083km) for the final position.

And the displacement will be:

D = √( (4.188km - 0)^2 + (1.083 - 0)^2) = 4.236km

5 0
3 years ago
When a raw egg gets heated into an edible egg is this considered a physical or chemical change?
sweet-ann [11.9K]

Answer:

it is a physical change

Explanation:

you aren't adding nothing to the egg it is only changing the looks from it you are not adding anything to make it go through a chemical change  

8 0
4 years ago
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A car moving along a straight highway it at speed of 144 km/h is brought to a within a distance of 200m..
arlik [135]

Answer:

I don't know this answer questions

4 0
3 years ago
The mass at time t of a radioactive substance is m(t)=m(0)ekt, where m(0) is the initial mass and k=−0.000135. The mean life M o
belka [17]

Answer:

7407.4 units

Explanation:

m(t) = m(0) e^kt

Here, k = - 0.000135

So, the above equation becomes

m(t) = m(0) e^(-0.000135 t)

Compare with the standard equation of radioactivity

m(t) = m(0) e^-λt

Where, λ be the decay constant

So. λ = 0.000135

The relation between the decay constant and the mean life is

ζ = 1 / λ

Where, ζ is the mean life

So, ζ = 1 / 0.000135 = 7407.4 units

4 0
4 years ago
the diagram shows three beakers with water . The first beaker has a block of cork in it . The second beaker has a block of wood
weeeeeb [17]

Answer: cork

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7 0
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