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3 years ago

8. What is the momentum of a 120-kg professional fullback running across the line at 11.2 m/s?

Physics

1 answer:

Alchen [17]3 years ago

5 0

Answer:

134r kgm^-1 or 1344 kg /m

Explanation:

Momentum is is given by:

p=mv

Where:

p is momentum, m is mass in kg and v is velocity in ms−1

p=120kg×11.2 m/ s= 1344 kgms=1344kgm^−1

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6. A car is traveling at 50m/s when it begins to slow down to

ki77a [65]

Answer:

-6 m/s²

Explanation:

Given:

v₀ = 50 m/s

v = 20 m/s

t = 5 s

Find: a

v = at + v₀

20 m/s = a (5 s) + 50 m/s

a = -6 m/s²

8 0

3 years ago

If a heat engine takes in 4565 kJ and gives up 2955 kJ during one cycle, what is the engine’s efficiency?

vodomira [7]

The engine efficiency is 64.73 %

Explanation:

Given data

To find the engine’s efficiency we have the formula,

Energy input- 4565 KJ

Energy output - 2955KJ

Efficiency= energy output/ energy input ×100%

=2955/4565

=0.6473 ×100

η =64.73 %

The engine efficiency is 64.73 %

5 0

3 years ago

A block of wood of mass 24 kg floats on water. The volume of the block below the surface of the water and the density of the woo

Slav-nsk [51]

Answer:

0.024m^3

Explanation:

=======

Answer:

=======

Given:-

Mass of the block of wood = 24 kg

Volume of wood = 0.032 m^3

Density of water = 1000kg/m^3

Now,

Density of wood is given by,

\frac{m}{v} = \frac{24}{0.032} \\

\frac{m}{v} = 750 \: kg/m ^{3}

Therefore,

The density of wood is 750kg/m^3

By principle of floatation,

Mass \:of\: wood = Mass\: of\: liquid \:displaced

Therefore,

Mass of liquid displaced = 24kg

Volume of liquid displaced (v),

\frac{m}{v} = \frac{24}{1000} \\

\frac{m}{v} = 0.24m ^{3}

Now,

Since the volume of the wood is equal to the volume of water displaced, it is 0.024m^3

=====

Note:

=====

=> The volume of the wood below the water surface is the volume of water displaced.

=> Buoyant\: force = Weight\: of\: the \:displaced\: water.

8 0

3 years ago

1. If a system is isolated, the total energy within that system is constant. Consider the case of a hot cup of coffee: when it c

nignag [31]

Answer:

1. B. The person and the Earth

2. This is because the energy gained by the person equals the energy lost by the earth,

Explanation:

B. The person and the Earth

This is because the person and the earth both represent a system. A system consists of more than one item. A system consists of two or more items interacting with each other.

2. This is because, the energy of an isolated system is conserved according to the second law of thermodynamics which states that in an isolated system, energy can neither be created nor destroyed. So, there is an exchange of energy between the person and the Earth. So, the energy gained by the person at the new height equals the energy lost by the earth. And thus, the total energy of the system remains constant.

6 0

3 years ago

In which situation is work being done?

Keith_Richards [23]

Answer: D. The force and displacement are in the same direction.

Explanation:

The Work $W$ done by a Force $F$ refers to the release of potential energy from a body that is moved by the application of that force to overcome a resistance along a path with distance $d$ .

Work is a scalar magnitude, and its unit in the International System of Units is the Joule (like energy).

Now, when the applied force is constant and the direction of the force and the direction of the displacement are parallel, the equation to calculate it is:

$W=(F)(d)$ (1)

When they are not parallel, both directions form an angle, let's call it $\alpha$ . In that case the expression to calculate the Work is:

$W=Fdcos{\alpha}$ (2)

When the force and displacement are perpendicular to each other, $\alpha=90\°$ and no work is done.

4 0

3 years ago