Using Newton’s second law, why do you think a cotton ball may not be used as a baseball in a baseball game.

Suppose you see two main-sequence stars of the exact same spectral type. Star 1 is dimmer in apparent brightness than Star 2 by

katrin2010 [14]

Options:

A. The luminosity of Star 1 is a factor of 100 less than the luminosity of Star 2.

B. Star 1 is 100 times more distant than Star 2.

C. Without first knowing the distances to these stars, you cannot draw any conclusions about how their true luminosities compare to each other.

D. Star 1 is 10 times more distant than Star 2.

E. Star 1 is 100 times nearer than Star 2.

Answer:

D. Star 1 is 10 times more distant than star 2

Explanation:

For two stars of identical size and temperature, the closer one to us will appear brighter. The relationship between the distance and luminosity of stars is an inverse- square relationship.

Luminosity, L = 1/r²

Where r is the distance of the star to the earth

Since star 1 is dimmer in brightness than star 2 by a factor of 100,

L₁/L₂ = 1/100

i.e. L₁ = 1, L₂=100

L₁ = 1/r₁² ............(1)

1 = 1/r₁²

L₂ = 1/r₂²

100 = 1/r₂² .........(2)

divide equation (2) by equation (1)

100/1 = ( 1/r₂² )/ (1/r₁²)

100 = (r₁/r₂)²

r₁/r₂ = √100

r₁/r₂ = 10

r₁ = 10r₂

3 0

1 year ago

Suppose that a freely falling object were somehow equipped with an odometer. Would the readings of distance fallen each second i

maks197457 [2]

Answer:

1 greater distances fallen in successive seconds

Explanation:

When a body falls freely it is subjected to the action of the force of gravity, which gives an acceleration of 9.8 m / s2, consequently, we are in an accelerated movement

If we use the kinematic formula we can find the position of the body

Y = Vo t + ½ to t2

Where the initial velocity is zero or constant and the acceleration is the acceleration of gravity

Y = - ½ g t2 = - ½ 9.8 t2 = -4.9 t2

Let's look for the position for successive times

t (s) Y (m)

1 -4.9

2 -19.6

3 -43.2

The sign indicates that the positive sense is up

It can be clearly seen that the distance is greatly increased every second that passes

3 0

2 years ago

The SI units for measuring the velocity of the car: The SI units for measuring the acceleration of the car: The SI units for mea

klasskru [66]

Velocity ... m/s (meters per second) and angle

Acceleration ... m/s^2 and angle

Force ... Newton (kg-m/s^2) and angle

Mass ... kilogram

3 0

1 year ago

Read 2 more answers

A 94-ft3/s water jet is moving in the positive x-direction at 18 ft/s. The stream hits a stationary splitter, such that half of

vitfil [10]

Answer:

FRx = 960.37 lbf (←)

FRz = 0 lbf

Explanation:

Given:

Q = 94 ft³/s

vx = 18 ft/s

ρ = 62.4 lbm/ft³

∅ = 45°

Assumptions:

1. The flow is steady and incompressible.

2 . The water jet is exposed to the atmosphere, and thus the pressure of the water jet before and after the split is the atmospheric pressure which is disregarded since it acts on all surfaces.

3. The gravitational effects are disregarded.

4. The flow is nearly uniform at all cross sections, and thus the effect of the momentum-flux correction factor is negligible, β ≅ 1.

Properties: We take the density of water to be ρ = 62.4 lbm/ft³

Analysis: The mass flow rate of water jet is

M = ρ*Q = (62.4 lbm/ft³ )(94 ft³/s) = 5865.6 lbm/s

We take the splitting section of water jet, including the splitter as the control volume, and designate the entrance by 1 and the outlet of either arm by 2 (both arms have the same velocity and mass flow rate M). We also designate the horizontal coordinate by x with the direction of flow as being the positive direction and the vertical coordinate by z.

The momentum equation for steady flow is

∑ F = ∑ (β*M*v) out - ∑ (β*M*v) in

We let the x- and y- components of the anchoring force of the splitter be FRx and FRz, and assume them to be in the positive directions. Noting that

v₂ = v₁ = v and M₂ = (1/2) M, the momentum equations along the x and z axes become

FRx = 2*(1/2) M*v₂*Cos ∅ - M*v₁ = M*v*(Cos ∅ - 1)

FRz = (1/2) M*(v₂*Sin ∅) + (1/2) M*(-v₂*Sin ∅) = 0

Substituting the given values,

FRx = (5865.6 lbm/s)*(18 ft/s)*(Cos (45°) - 1)(1 lbf / 32.2 lbm*ft/s²)

⇒ FRx = - 960.37 lbf

FRz = 0 lbf

The negative value for FRx indicates the assumed direction is wrong, and should be reversed. Therefore, a force of 960.37 lbf must be applied to the splitter in the opposite direction to flow to hold it in place. No holding force is necessary in the vertical direction. This can also be concluded from the symmetry.

In reality, the gravitational effects will cause the upper stream to slow down and the lower stream to speed up after the split. But for short distances, these effects are negligible.

3 0

2 years ago

A typical machine tests the tensile strength of a sheet of material cut into a standard size of 5.00 centimeters wide by 10.0 ce

Minchanka [31]

Answer:

Explanation:

tensile strength is stress that is needed to break the wire made of the material .

Here force required to break the sheet of material = 233 N

cross sectional area of the foil = breadth x thickness

= 5 x 10⁻² x 15 x 10⁻⁶ m²

= 75 x 10⁻⁸ m²

breaking stress = force / cross sectional area

= 233 / 75 x 10⁻⁸

= 3.1 x 10⁸ Pa .

Tensile strength = 3.1 x 10⁸ Pa .

4 0

2 years ago