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3 years ago

What happens when a roller coaster car moves down from the top of a hill?

2 answers:

6 0

-- It accelerates.
-- Its speed increases.
-- It gains momentum.
-- It loses altitude.
-- It loses potential energy.
-- It gains kinetic energy.
-- Its wheels make a lot of noise.
-- Everybody screams.

Stella [2.4K]3 years ago

3 0

Potential energy is transformed into kinetic and thermal energy.

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A 3.0-kg block starts at rest at the top of a 37° incline, which is 5.0 m long. Its speed when it reaches the bottom is 2.0 m/s.

Mama L [17]

Answer: $f_{r}$ = 16.49N

Explanation: The object is placed on an inclined plane at an angle of 37° thus making it weight have two component,

$W_{x}$ = horizontal component of the weight = mgsinФ

$W_{y}$ = vertical component of weight = mgcosФ

Due to the way the object is positioned, the horizontal component of force will accelerate the object thus acting as an applied force.

by using newton's law of motion, we have that

mgsinФ - $f_{r}$ = ma

where m = mass of object=5kg

a = acceleration= unknown

Ф = angle of inclination = 37°

g = acceleration due to gravity = 9.8 $m/s^{2}$

$f_{r}$ = frictional force = unknown

we need to first get the acceleration before the frictional force which is gotten by using the equation below

$v^{2} = u^{2} + 2aS$

where v = final velocity = 2m/s

u = initial velocity = 0m/s (because the object started from rest)

a= unknown

S= distance covered = length of plane = 5m

$2^{2} = 0^{2} + 2*a*5\\\\4= 10 *a\\\\a = \frac{4}{10} \\a = 0.4m/s^{2}$

we slot in a into the equation below to get frictional force

mgsinФ - $f_{r}$ = ma

3 * 9.8 * sin 37 - $f_{r}$ = 3* 0.4

17.9633 - $f_{r}$ = 1.2

$f_{r}$ = 17.9633 - 1.2

$f_{r}$ = 16.49N

4 0

3 years ago

Which of the following processes DOES NOT occur during the convective transfer of heat within a container of air? Group of answe

vovangra [49]

The volume of a warmed part of the air is reduced and its density increases.

Explanation:

In a convective form of heat transfer, the volume of a warmed part of air is not reduced and its density does not increase.

During convection, heat causes the warm part of the air to expand and its volume increases. When volume increases, density is reduced.

Convection is a form of heat transfer that involves the actual movement of particles of the medium.
It usually occurs in fluids i.e gases and liquids.
In convection, the cold part exerts a buoyant force on the warmer air below and causes it to rise.
As the warmer part is rising the cooler part replaces it and a convective cell is formed in the process.

Learn more:

Energy transfer in the sun brainly.com/question/1140127

#learnwithBrainly

7 0

3 years ago

1. How would you expect an instantaneous acceleration vs. time graph to look for a cart moving with a constant

r-ruslan [8.4K]

Answer:

a=0 v = v₀ + a t

a=0 line is horizontal

Explanation:

1, In a graph of acceleration vs. time, we have lines, when the line is horizontal it is zero, when the line has a positive slope the increasing accelerations and when the slope is negative the decreasing acceleration

2, speed and relationship of a car is given by

v = v₀ + a t

where vo is the initial velocity, a is the acceleration and tel time

in this case I will calcograph velocity vs. time the constant acceleration is a straight line.

In general from the graph we can find the initial velocity with the cut at that x and the acceleration of the car with the slope

6 0

3 years ago

The resistance, R, of a wire varies directly as its length and inversely as the square of its diameter. If the resistance of a w

lbvjy [14]

R is proportional to the length of the wire:

R ∝ length

R is also proportional to the inverse square of the diameter:

R ∝ 1/diameter²

The resistance of a wire 2700ft long with a diameter of 0.26in is 9850Ω. Now let's change the shape of the wire, adding and subtracting material as we go along, such that the wire is now 2800ft and has a diameter of 0.1in.

Calculate the scale factor due to the changed length:

k₁ = 2800/2700 = 1.037

Scale factor due to changed diameter:

k₂ = 1/(0.1/0.26)² = 6.76

Multiply the original resistance by these factors to get the new resistance:

R = R₀k₁k₂

R₀ = 9850Ω, k₁ = 1.037, k₂ = 6.76

R = 9850(1.037)(6.76)

R = 69049.682Ω

Round to the nearest hundredth:

R = 69049.68Ω

8 0

3 years ago

Evaporation only occurs at the surface of a liquid

Veseljchak [2.6K]

yes

evaporation starts on the surface

8 0

4 years ago