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3 years ago

A plane on the ground will weigh:

Physics

2 answers:

Arisa [49]3 years ago

6 0

Answer:

Yes the correct answer is A) more than a plane on air

kenny6666 [7]3 years ago

3 0

On ground weight of plane will be measured as its actual weight which will be given as

$W = mg$

now when plane is in air its weight is measured as combined effect of earth gravitational force and buoyancy force both

so weight in air will be given as

$W_{air} = mg - F_b$

here since net effect due to air is opposite to the direction of weight so in air the plane weight will be measure less than its weight on ground.

so answer will be

A)more than a plane in the air

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A group of rescue workers is rescuing a dog from a condemned building. Due to demolition, the building has no stairs leading to

zaharov [31]

Answer:

Minimize the elevation or jump distance

Explanation:

The only action that minimizes, the impact force is to reduce as much as possible the height of the jump, the dog, ie the height from the jump point of the building. Since at the time of the jump its speed will increase every second at the rate of 9 [m/ s], that is this low effect of the gravitational acceleration of 9 [m/s^2]

$v_{f}=\sqrt{2*g*h}$

where:

vf = final velocity [m/s]

g = gravity [m/s^2]

h = elevation [m]

As we can see while there is higher height, at a higher speed will impact the ground.

6 0

4 years ago

A reciprocating compressor is a device that compresses air by a back-and-forth straight-line motion, like a piston in a cylinder

Stella [2.4K]

Answer:

The temperature change per compression stroke is 32.48°.

Explanation:

Given that,

Angular frequency = 150 rpm

Stroke = 2.00 mol

Initial temperature = 390 K

Supplied power = -7.9 kW

Rate of heat = -1.1 kW

We need to calculate the time for compressor

Using formula of compression

$\terxt{time for compression}=\text{time for half revolution}$

$\terxt{time for compression}=\dfrac{1}{2}\times T$

$\terxt{time for compression}=\dfrac{1}{2}\times \dfrac{1}{f}$

Put the value into the formula

$\terxt{time for compression}=\dfrac{1}{2}\times \dfrac{1}{150}\times60$

$\terxt{time for compression}=0.2\ sec$

We need to calculate the rate of internal energy

Using first law of thermodynamics

$U=Q-W$

$\dfrac{\Delta U}{\Delta t}=\dfrac{\Delta Q}{\Delta t}-\dfrac{\Delta W}{\Delta t}$

Put the value into the formula

$\dfrac{\Delta U}{\Delta t}=(-1.1)-(7.9)$

$\dfrac{\Delta U}{\Delta t}=6.8\ kW$

We need to calculate the temperature change per compression stroke

Using formula of rate of internal energy

$\dfrac{\Delta U}{\Delta t}=\dfrac{nc_{v}\Delta \theta}{\Delta t}$

$\Delta\theta=\dfrac{\Delta U}{\Delta t}\times\dfrac{\Delta t}{n\times c_{c}}$

Put the value into the formula

$\Delta \theta=6.8\times10^{3}\dfrac{0.2}{2.0\times20.93}$

$\Delta\theta=32.48^{\circ}$

Hence, The temperature change per compression stroke is 32.48°.

6 0

4 years ago

A women who normally weighs 400 N stands on top of a ladder so high she is one full additional earth radius above the surface of

AveGali [126]

The woman weighs 100N now.

Explanation:

Given:

F is given as 400N

one full additional earth radius formed

To Find:

Weight of the woman=?

Solution:

We know that gravitational force is inversely proportional to the square of radius.

$f_g=\frac{1}{r^2}$

where

$f_g$ is the gravitational force

$r^2$ is the radius square

So when radius is doubled, the force becomes one fourth of the original.

Therefore $\frac{1}{4} \times400 = 100N$

3 0

3 years ago

Consider a lawnmower of mass m which can slide across a horizontal surface with a coefficient of friction μ. In this problem the

inna [77]

Answer:

Fh = u*m*g / (cos(θ) - u*sin(θ))

Explanation:

Given:

- The mass of lawnmower = m

- The angle the handle makes with the horizontal = θ

- The force applied along the handle = Fh

- The coefficient of friction of the lawnmower with ground = u

Find:

Find the magnitude, Fh, of the force required to slide the lawnmower over the ground at constant speed by pushing the handle.

Solution:

- Construct a Free Body Diagram (FBD) for the lawnmower.

- Realize that there is horizontal force applied parallel to ground due to Fh that drives the lawnmower and a friction force that opposes this motion. We will use to Newton's law of motion to express these two forces in x-direction as follows:

F_net,x = m*a

- Since, the lawnmower is to move with constant speed then we have a = 0.

F_net,x = 0

- The forces as follows:

Fh*cos(θ) - Ff = 0

Where, Ff is the frictional force:

Fh = Ff /cos(θ)

Similarly, for vertical direction y the forces are in equilibrium. Using equilibrium equation in y direction we have:

- W - Fh*sin(θ) + Fn = 0

Where, W is the weight of the lawnmower and Fn is the contact force exerted by the ground on the lawnmower. Then we have:

Fn = W + Fh*sin(θ)

Fn = m*g + Fh*sin(θ)

The Frictional force Ff is proportional to the contact force Fn by:

Ff = u*Fn

Ff = u*(m*g + Fh*sin(θ))

Substitute this expression in the form derived for Fh and Ff:

Fh*cos(θ) = u*(m*g + Fh*sin(θ))

Fh*(cos(θ) - u*sin(θ)) = u*m*g

Fh = u*m*g / (cos(θ) - u*sin(θ))

5 0

3 years ago

What two properties show that the drink is a fluid ( girl drinking fruit punch out of a clear glass cup with a straw.)

Ainat [17]

It takes the shape of the cup and it can be sucked through a straw

3 0

4 years ago

Read 2 more answers