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icang [17]
3 years ago
12

A roundabout in a fairground requires an input power of 2.5 kW when operating at a constant angular velocity of 0.47 rad s–1 . (

a) Show that the frictional torque in the system is about 5 kN m. (3) 1. (b) When the power is switched off, the roundabout decelerates uniformly because the
Physics
1 answer:
natita [175]3 years ago
5 0

Answer:

Explanation:

Since the roundabout is rotating with uniform velocity ,

input power = frictional power

frictional power = 2.5 kW

frictional torque x angular velocity = 2.5 kW

frictional torque x .47 = 2.5 kW

frictional torque = 2.5 / .47 kN .m

= 5.32 kN . m

= 5 kN.m

b )

When power is switched off , it will decelerate because of frictional torque .

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A skater with a mass of 72 kg is traveling east at 5.8 m/s when he collides with another skater of mass 45 kg heading 60° south
Akimi4 [234]

The final velocity is 5.87 m/s

<u>Explanation:</u>

Given-

mass, m_{1} = 72 kg

speed, v_{1} = 5.8 m/s

Mass_{2},m_{2}  = 45 kg

speed_{2},v_{2}  = 12 m/s

Θ = 60°

Final velocity, v = ?

Applying the conservation of momentum:

m_{1} X v_{1} + m_{2} X v_{2} = (m_{1} +m_{2} ) v

72 X 5.8 + 45 X 12 X cos 60° = (72 + 45) v

v = 417.6 + 540 X \frac{0.5}{117}

v = 417.6 + \frac{270}{117}

v = 5.87 m/s

The final velocity is 5.87 m/s

8 0
3 years ago
By what factor would your weight be multiplied if the earth were1/2 as massavise and the diameter was unchanged
Nutka1998 [239]
<span>Let F be the force of gravity, G be the gravitational constant, M be the mass of the earth, m your mass and r the radius of the earth, then: 

F = G(Mm / (4(pi)*r^2)) 

The above expression gives the force that you feel on the earth's surface, as it is today! 

Let us now double the mass of the earth and decrease its diameter to half its original size. 

This is the same as replacing M with 2M and r with r/2. 

Now the gravitational force (F' ) on the new earth's surface is given by: 

F' = G(2Mm / (4(pi)(r/2)^2)) = 2G(Mm / ((1/4)*4(pi)*r^2)) = 8G(Mm / (4(pi)*r^2)) = 8F 

So: 

F' = 8F 

This implies that the force that you would feel pulling you down (your weight) would increase by 800%! 

You would be 8 times heavier on this "new" earth!</span>
4 0
3 years ago
What is the momentum of a 200 kg football player running west at a speed of 8m/s
lutik1710 [3]

Answer:

<h3>The answer is 1600 kgm/s</h3>

Explanation:

The momentum of an object can be found by using the formula

<h3>momentum = mass × velocity</h3>

From the question

mass = 200 kg

velocity / speed = 8m/s

We have

momentum = 200 × 8

We have the final answer as

<h3>1600 kgm/s</h3>

Hope this helps you

7 0
4 years ago
Please help
WITCHER [35]

Gravity is the force that pulls you down.
(This is kind of a duh! question ... How do we know
which way is "down" ?  We feel gravity, and we call
that the "down" direction.)

Magnetic force holds things to fridge doors.

Contact forces need to touch something in order to
exert their force.
Example:  Gravity is NOT a contact force.

I don't know about "rubbing things away".
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it's not a good one.

Buoyant force is what keeps floating things floating.

Air resistance slows things down when they move in air.

4 0
4 years ago
What observations tell you that a car is accelerating
professor190 [17]
When the car moves and makes a sound that is louder that when the car is just sitting there
8 0
3 years ago
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