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2 years ago

1) Which of the following explains why a bicycle uses a gear?

2 answers:

7 0

1. "The gear decreases effort force" is the one among the following choices given in the question that explains why a bicycle uses a gear. The correct option among all the options is option "C".

2. A can opener is a compound machine. The correct option among all the options that are given in the question is the second option or option "B".

Marta_Voda [28]2 years ago

4 0

Answer:

1) D. The gear decreases resistance force

2) B. A car opener

Explanation:

1): A bicycle uses a gear to decrease the resistance force as when the gears are shifted, the chain moves from a larger ring to a smaller one thus reducing the surface area of the ring as well as friction which results into a greater speed by applying same amount of effort.

2): As a compound machine is a combination of more than one simple machine. Out of all the options, a car opener is said to be a compound machine as it consist of a lever, screw, wedge and axle and wheel.

These are some of the simple machines which combines to make a complex machine ( car opener ).

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A 2:2 kg toy train is con ned to roll along a straight, frictionless track parallel to the x-axis. The train starts at the origi

Liula [17]

Answer:

a) 10.51 J

b) 3.48 m/s

Explanation:

Given data :

mass of train ( M ) = 2.2 kg

Given initial velocity ( u ) = 1.6 m/s

a) calculating work done by the force over the journey of the train

F = mx + b ------ ( 1 )

m = slope = ( Δ f / Δ x ) = 2.8 / -7.5 = - 0.373 N/m

x = distance travelled on the x axis by the train = 7.5 m

F = force experienced by the train = 2.8 N

x = 0

∴ b = 2.8

hence equation 1 can be written as

F = ( -0.373) x + 2.8 ----- ( 2 )

hence to determine the work done by the force

W = $\int\limits^7_0 { ( -0.373) x + 2.8 )} \, dx$ Note: the limits are actually 7.5 and 0

∴ W ( work done ) = -10.49 + 21 = 10.51 J

b) calculate the speed of the train at the end of its journey

we will apply the work energy theorem

W = 1/2 m*v^2 - 1/2 m*u^2

∴ V^2 = 2 / M ( W + 1/2 M*u^2 ) ( input values into equation )

V^2 = 12.11

hence V = 3.48 m/s

6 0

2 years ago

Using equations, determine the temperature, pressure and density of the air for a aircraft flying at 19.5 km. Is this aircraft s

Viefleur [7K]

Answer:

a) - 72.5°c

b) pressure = 3625.13 Pa

c) density = 0.063 kg/m^3

d) it is a subsonic aircraft

Explanation:

a) Determine Temperature

Temperature at 19.5 km ( 19500 m )

T = -131 + ( 0.003 * altitude in meters )

= -131 + ( 0.003 * 19500 ) = - 72.5°c

b) Determine pressure and density at 19.5 km altitude

Given :

Po (atmospheric pressure at sea level ) = 101kpa

R ( gas constant of air ) = 0.287 KJ/Kgk

T = -72.5°c ≈ 200.5 k

pressure = 3625.13 Pa

hence density = 0.063 kg/m^3

attached below is the remaining part of the solution

C) determine if the aircraft is subsonic or super sonic

Velocity ( v ) = $\sqrt{CRT}$ = $\sqrt{1.4*287*200.5 }$ = 283.8 m/s

hence it is a subsonic aircraft

4 0

2 years ago

Why are many adults and youth in the United states overweight?

Anna11 [10]

Answer:

I'd imagine fast food is a lot more popular than most countries over there and easier to get hold of.

Explanation:

america

6 0

2 years ago

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A 30.0 kg dolphin decelerates from 12.0 to 7.00 m/s in 2.60 s to join another dolphin in play. What average force (in N) was exe

Crazy boy [7]

Answer:

Force is 57.69 N to the opposite direction of motion of dolphin.

Explanation:

We have force is the product of mass and acceleration.

That is

Force = Mass x Acceleration

F = ma

Mass of dolphin, m = 30 kg

We have equation of motion, v = u + at

Final velocity, v = 7 m/s

Initial velocity, u = 12 m/s

Time, t = 2.60 s

Substituting

7 = 12 + a x 2.6

a = -1.92 m/s²

Force, F = 30 x -1.92 = -57.69 N

So the force is 57.69 N to the opposite direction of motion of dolphin.

7 0

2 years ago

How many meters does it take to make one mile

rjkz [21]

Answer:

1610 meters

Explanation:

4 0

2 years ago

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