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3 years ago

Assume that g is 10 N/kg and that air resistance and other

Physics

1 answer:

nirvana33 [79]3 years ago

3 0

Answer:

1) Given acceleration due to gravity as 10N/kg

N/kg is the same as m/s². From W=mg

making g subject ... you have g = W/m

where m is in kg and W is in N

hence we have N/kg

So g=10ms-²

Gravitational Potential Energy=mgh

At height 4m

PE=6 x 10 x 4

=240J.

At height 6m

PE=6 x 10 x 6

=360J.

2) KE=1/2mv²

=1/2 x 6 x 5² =75J

When the speed is doubled... it becomes 2x

so V = 2x5=10ms-¹

KE=1/2 x 6 x 10² =300J.

3) KE=1/2mv²

KE is given as 100J

mass=0.5kg

Making V the subject

you have v² =2KE/m

v²=2 x 100/0.5

v²=400

taking square root

v=20ms-¹.

Have a great day✌

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An inventor claims to have invented a heat engine that receives 750kJ of heat from a source at 400K and produces 250kJ of net wo

IRISSAK [1]

Answer:

the claim is not valid or reasonable.

Explanation:

In order to test the claim we will find the maximum and actual efficiencies. maximum efficiency of a heat engine can be found as:

η(max) = 1 - T₁/T₂

where,

η(max) = maximum efficiency = ?

T₁ = Sink Temperature = 300 K

T₂ = Source Temperature = 400 K

Therefore,

η(max) = 1 - 300 K/400 K

η(max) = 0.25 = 25%

Now, we calculate the actual frequency of the engine:

η = W/Q

where,

W = Net Work = 250 KJ

Q = Heat Received = 750 KJ

Therefore,

η = 250 KJ/750 KJ

η = 0.333 = 33.3 %

η > η(max)

The actual efficiency of a heat engine can never be greater than its Carnot efficiency or the maximum efficiency.

<u>Therefore, the claim is not valid or reasonable.</u>

3 0

3 years ago

A beaker weighs 0.4N when empty and1.4N when filled with water what does ot weigh when filled with brine of density 1.2 g/cm3

PtichkaEL [24]

Answer:2.47

Explanation:

So, the beaker weighs 1.40N when filled with water, brine of density weighs about 1.7N, you add the density + water. Have a good day!

7 0

3 years ago

What is the meaning of viscosity?

Vera_Pavlovna [14]

the state of being thick, sticky, and semifluid in consistency, due to internal friction.

5 0

3 years ago

In 5 meters, a person running at 0.8 m/s accelerates at 1.6 m/s2. How fast 16 points

frutty [35]

They were going at a velocity 4.07m/s

<u>Explanation:</u>

Distance s =5 m

initial velocity u= 0.8 m/s

Acceleration a =1.6m/s2

We have to calculate the velocity with which they were going afterwards i.e final velocity.

Use the equation of motion

$v^2=u^2+2as\\=0.8^2+2\times 1.6\times 5\\=16.64\\v=4.07 m/s$

They were going with a velocity 4.07 m/s afterwards.

5 0

3 years ago

An object is placed 5.00 cm beyond the focal point of a convex lens whose focal length is 10.0 cm. If the object height is 3.0 c

Aleks04 [339]

Answer:

The height of the image is, h' = 6.0 cm

The image is erect.

Explanation:

Given data,

The object distance, u = -5 cm

The focal length of convex lens, f = 10 cm

The object height, h = 3 cm

The lens formula,

$\frac{1}{f}=\frac{1}{v}-\frac{1}{u}$

$\frac{1}{10}=\frac{1}{v}-\frac{1}{-5}$

$\frac{1}{v}=\frac{1}{10}-\frac{1}{5}$

v = -10 cm

The magnification factor of lens

$m=\frac{-10}{-5}$

m = 2

$m=\frac{h'}{h}$

$h'=h\times m$

$h'=3\times 2$

h' = 6 cm

The height of the image is, h' = 6 cm

The image is erect.

4 0

3 years ago