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2 years ago

In some circumstances, science will answer questions about what is good and what is evil.

Physics

1 answer:

Margaret [11]2 years ago

3 0

False, its up to you to decide what you belive is right and what is wrong.

You might be interested in

A man in a gym is holding an 8.0-kg weight at arm's length, a distance of 0.55 m from his shoulder joint. What is the torque abo

kipiarov [429]

Answer:

$\tau =37.34\ N m$

Explanation:

given,

mass of the weight = 8 Kg

distance = 0.55 m

angle below horizontal = 30°

torque about shoulder

$\tau = \vec{r} \times \vec{F}$

$\tau = r \times F cos \theta$

$\tau = 0.55 \times 8 \times 9.8 \times cos 30^0$

$\tau =37.34\ N m$

torque about his shoulder join is equal to $\tau =37.34\ N m$

5 0

3 years ago

A massless spring with force constant ????=200N/m hangs from the ceiling. A 2.0-kg block is attached to the free end of the spri

Makovka662 [10]

Answer:

-0.4454 Joules

Explanation:

m = Mass of block = 2 kg

h = Height of extension = 17 cm = x

g = Acceleration due to gravity = 9.81 m/s²

Potential energy of the spring

$P=mgh\\\Rightarrow P=2\times 9.81\times 0.17\\\Rightarrow P=3.3354\ J$

The kinetic energy of the spring

$K=\frac{1}{2}mx^2\\\Rightarrow K=\frac{1}{2}\times 200\times 0.17^2\\\Rightarrow K=2.89\ J$

In this system as the potential and kinetic energy is conserved from work energy equivalence we get

$W=P-K\\\Rightarrow W=2.89-3.3354\\\Rightarrow W=-0.4454\ J$

The work done by friction is -0.4454 Joules

8 0

2 years ago

A city planner needs to make a model of the city. In real life, the tallest tree in the city is 40 feet tall. The shortest tree

Verdich [7]

To solve this you must set up what is called a proportion. A proportion is a way of comparing two comparing values where one of the four values is missing. In your problem the missing value is the height of the smallest tree in the model.

To set up a proportion, you need all of your values. The easiest way to do this is to list them:

Highest tree in real life: 40ft
Highest tree in model: 10ft
Smallest tree in real life: 4ft
Smallest tree in model: x

So know you can set your proportion like this:

40/4 = 4/x

(When setting up a proportion, you always want to have the values belong to each other. For example don't put the height of the small tree in the model underneath the value of the highest tree in real life.)

So know to find what the x values equals, we need to cross multiply. And then all that's left after that is to solve for x.

40 times x = 4 times 4

40x = 16

x = 2.5

The smallest tree in the model should equal 2.5 feet.

Hope this helps! :)

6 0

2 years ago

A hot-water stream at 80 ℃ enters a mixing chamber with a mass flow rate of 0.5 kg/s where it is mixed with a stream of cold wat

rewona [7]

Answer:

$\dot{m_{2}}=0.865 kg/s$

Explanation:

$\dot{m_1}= 0.5kg/s$

from steam tables , at 250 kPa, and at

T₁ = 80⁰C ⇒ h₁ = 335.02 kJ/kg

T₂ = 20⁰C⇒ h₂ = 83.915 kJ/kg

T₃ = 42⁰C ⇒ h₃ = 175.90 kJ/kg

we know

$\dot{m_{in}}=\dot{m_{out}}$

$\dot{m_{1}}+\dot{m_{2}}=\dot{m_{3}}$

according to energy balance equation

$\dot{m_{in}}h_{in}=\dot{m_{out}}h_{out}$

$\dot{m_{1}}h_{1}+\dot{m_{2}}h_{2}=\dot{m_{3}}h_{3}$

$\dot{m_{1}}h_{1}+\dot{m_{2}}h_{2}=(\dot{m_{1}}+\dot{m_{2}})h_{3}\\(0.5\times 335.02)+(\dot{m_{2}}\times 83.915)=(0.5+\dot{m_{2}})175.90\\\dot{m_{2}}=0.865 kg/s$

4 0

3 years ago

A hydraulic lift raises 1140 kg car through a height of 2.4 m. What is the potential energy

Sladkaya [172]

1140x9.8x2.4= 26,812.8 significant figures Make it 27,000

5 0

1 year ago