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2 years ago

How are metal bridges built to cope with changes of temperature?

1 answer:

8 0

As the metal expands as does the road bed so neither really effevts those foing over the bridge. as it is hot the metal will expand and so will most tarmac on roads.

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Harry Potter is chasing his nemesis Draco Malfoy during a quidditch match. Initially, Harry is 35m behind Draco, who has just sp

Sophie [7]

Answer:

the acceleration of harry is equal to 66.126 m/s²

Explanation:

given,

harry is 35 m behind Draco

speed of Draco = 40 m/s

original speed of harry = 50 m/s

acceleration = ?

time taken by the Draco

t = $\dfrac{r}{u} =\dfrac{75}{40}$

t = 1.875 s

distance covered by Harry

d = 35 + 175 = 210 m

to calculate the acceleration of harry

$s = u t+ \dfrac{1}{2}at^2$

$210 = 50\times 1.875+ \dfrac{1}{2}\times a\times 1.875^2$

a × 3.516 × 0.5 = 116.25

a = 66.126 m/s²

hence, the acceleration of harry is equal to 66.126 m/s²

3 0

3 years ago

A nonzero net force acts on a particle and does work. Which one of the following statements is true?

arlik [135]

Answer:

option (D) is correct.

Explanation:

According to the work energy theorem, the work done by all forces is equal to the change in kinetic energy of the body.

the kinetic energy of a body is directly proportional to the square of the speed of the body.

As the kinetic energy change, the speed of the body also change.

Option (D) is correct.

5 0

3 years ago

A rural mail carrier logged the mileage on the odometer at the start of the mail route as 31,500 miles. After 6.5 hours, the car

dusya [7]

Answer: $32.77\ mi/hr$

Explanation:

Given

Initially Reading on the odometer is $31,500\ miles$

Final reading on the odometer is $31,713\ miles$

Time taken is $t=6.5\ hr$

average velocity $=\dfrac{\text{Displacement}}{\text{time}}$

$v_{avg}=\dfrac{31713-31500}{6.5}$

$v_{avg}=\dfrac{213}{6.5}$

$v_{avg}=32.77\ mi/hr$

Thus the average velocity of mail truck is $32.77\ mi/hr$

8 0

3 years ago

A horizontal 953 N merry-go-round of radius 1.68 m is started from rest by a constant horizontal force of 73.9 N applied tangent

solniwko [45]

Answer:

K.E=365.2 J

Explanation:

Given data

Weight w =953 N

radius r=1.68 m

F=73.9 N

t=2.55 s

g=9.8 m/s²

To find

Kinetic Energy K.E

Solution

From the moment of inertia

$I=(1/2)MR^{2}\\ as \\W=mg\\So\\I=(1/2)(W/g)R^{2}\\I=(1/2)(953/9.8)(1.68)^{2}\\I=137.232kg.m^{2}$

The angular acceleration is given as

$a=T/I\\a=\frac{FR}{I}\\ a=\frac{(73.9)(1.68)}{137.232}\\a=0.905rad/s^{2}$

The angular velocity is given as

$w=at\\w=(0.905)(2.55)\\w=2.31rad/s$

So the Kinetic Energy is given as

$K.E=(1/2)Iw^{2}\\ K.E=(1/2)(137.232)(2.31)^{2}\\ K.E=365.2J$

3 0

3 years ago

If we assume that, in the African savanna, rainfall and the amount of grass is plentiful, what other factor would BEST explain a

valentina_108 [34]

Diseases, Hunting (sport for humans), predators

8 0

3 years ago

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