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3 years ago

8

A helicopter is hovering at a constant height of 35 m. The upward lift force on the helicopter is 85500. What is the weight of t

he helicopter

1 answer:

Vika [28.1K]3 years ago

7 0

2,442! I think..right ok

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Find the kinetic energy of a 0.1 kg toy truck moving at a speed of 1.1 m/s

enot [183]

0.0605J is your answer. Use the formula KE=1/2mv^2

8 0

4 years ago

A space vehicle is traveling at 3760 km/h relative to Earth when the exhausted rocket motor is disengaged and sent backward. The

almond37 [142]

Answer:

3688 km/h

Explanation:

Given:-

- The speed of vehicle relative to earth, vs_e = 3760 km/h

- The relative speed of command and motor, v_c/m = 90 km/h

- The mass of command = m

- The mass of motor = 4m

Find:-

What is the speed of the command module relative to Earth just after the separation?

Solution:-

- Consider the space vehicle as a system that detaches itself into two parts ( command and motor ). We will assume that the gravitational pull due to Earth on the space vehicle is negligible. With that assumption we have our system in isolation. We will apply the principle of conservation of linear momentum on the system as follows:

Initial momentum = Final momentum

Pi = Pf

M*vs_e = m*vc_e + 4m*vm_e

Where,

M = m + 4m = 5m

vc_e = Velocity of command relative to earth

vm_e = Velocity of motor relative to earth

- We will develop a relation of velocities of command and motor in the frame of earth as follows:

vm_e = v_c/m + vc_e

- Substituting (vm_e) from Equation 2 into Equation 1, we have:

5m*vs_e = m*vc_e + 4m*(v_c/m + vc_e)

5m*vs_e = 5m*vc_e + 4m*(v_c/m)

- Solve for vc_e:

5m*vs_e - 4m*(v_c/m) = 5m*vc_e

vs_e - 0.8*(v_c/m) = vc_e

- Plug in values and evaluate vc_e:

vc_e = 3760 - 0.8*(90)

vc_e = 3,688 km/h

5 0

3 years ago

Read 2 more answers

True or false. The planet's speed never changes. That is why we have a stable orbit.

Svetradugi [14.3K]

This answer is true the earth always stays at one speed

8 0

2 years ago

A 81 kg person sits on a 3.8 kg chair. Each leg of the chair makes contact with the floor in a circle that is 1.2 cm in diameter

tankabanditka [31]

Answer:

1.9 MPa

Explanation:

Mass of person = 81 kg

Mass of chair = 3.8 kg

Diameter of contact point = 1.2 cm = D

Radius of contact point = 1.2/2 = 0.6 cm

Total mass of chair and person = 81 + 3.8 = 84.8 kg = M

Acceleration due to gravity = 9.81 m/s²

Force acting on the floor

<em>F = Mg</em>

<em>⇒F = 84.8×9.81</em>

<em>⇒F = 831.888 N</em>

Area of the contact point

<em>A = πR²</em>

<em>⇒A = π0.006²</em>

<em>⇒A = π0.000036 m²</em>

Area of the four points is

<em>4A = 0.000144π m²</em>

Pressure

$p=\frac{F}{A}\\\Rightarrow p=\frac{831.888}{0.000144\pi}\\\Rightarrow p=1838876.21\ Pa=1.83887621\times 10^6\ Pa=1.9 MPa$

Pressure exerted on the floor by each leg of the chair is 1.9 MPa

5 0

3 years ago

Does the air exert a buoyant force on all objects in air or only on objects such as balloons that are very light for their size?

Citrus2011 [14]

Answer:

See explanation

Explanation:

Solution:-

Buoyancy is the force that causes objects to float. It is the force exerted on an object that is partly or wholly immersed in a fluid. Buoyancy is caused by the differences in pressure acting on opposite sides of an object immersed in a static fluid. It is also known as the buoyant force. Buoyancy is the phenomena due to Buoyant Force.

It is as an upward force exerted by a fluid that opposes the weight of an object immersed in a fluid. As we know, the pressure in a fluid column increases with depth. Thus, the pressure at the bottom of an object submerged in the fluid is greater than that at the top. The difference in this pressure results in a net upward force on the object which we define as buoyancy.

- The formula for buoyant force (Fb) is given:

Fb = ρ*g*V

- The force acts on all objects. However, it depends on the fluid density and amount of volume displaced.

- The Buoyant force exerted by air with density = 1.225 kg/m^3 on an object with volume (V) is:

Fb = ρ*g*V = 1.225*9.81*V = 12.02*V

- For the similar object with mass (m), the downward weight would be:

W = m*g

- For the object to float the buoyant force (Fb) must be greater than weight of the object:

Fb > W

12.02*V > m*9.81

V / m > 0.816

- The ratio of V / m must be at-least = 0.816.

- Assuming the object is fully immersed in air, then the volume displaced V = ρ_material*V

ρ_material < 1 / 0.816

ρ_material < 1.225 or ( ρ_air )

- So the for an object to float in air its material density must always be less than that of air. That why in balloons lighter gas is used which have density less than that of air like Helium.

4 0

3 years ago