2 Pete is driving down 7th street, He drives 150 meters in 18 seconds, Asaimning he does not speed up or

Which option correctly defines the scientific method?

andreev551 [17]

The option that BEST correctly defines the scientific method is option C.

5 0

4 years ago

A portion of the atmosphere that becomes warmer than surrounding air will ____.

earnstyle [38]

<span>A portion of the atmosphere that becomes warmer than surrounding air will expand and rise. The warmer atmosphere the more space between the molecules. Therefore, warmer atmosphere </span><span>expands to allow more space for the molecules. Cool air on the other hand, contracts because the molecules in cool air need less space.</span>

3 0

3 years ago

A 2.4 kg box has an initial velocity of 3.6 m/s upward along a plane inclined at 27◦ to the horizontal. The coefficient of kinet

Vika [28.1K]

Answer:

d= 1.18 m

Explanation:

In abscense of friction, total mechanical energy must be constant, i.e.,

ΔK + ΔU = 0

As we are told that there exists a kinetic friction between the box and the plane, we need to take into account the work done by the friction force in the equation, as follows:

ΔK + ΔU = Wnc (1)

If we take as our zero gravitational potential energy reference, the height at which the box is sent upward, we can write the following equations for the different terms in (1):

ΔK = Kf- K₀ = 0 - 1/2*m*v₀² = -1/2*2.4kg* (3.6)²(m/s)² = -15.6 J

ΔU = Uf - U₀ = m*g*h = *m*g*d*sin θ = 2.4 kg*9.81 m/s²*d*0.454 = 10.7*d J

Wnc = Ff. d* cos (180º) = μk*N*d*cos(180º) (2)

The friction force always opposes to the displacement, so the angle between force and displacement is 180º.

The normal force, as is always perpendicular to the surface, takes the value needed to equilibrate the component of the weight perpendicular to the incline, as follows:

N = m*g*cosθ = 2.4 kg*9.81 m/s²*cos 27º = 21 N

Replacing in (2):

Wnc = 0.12*21*cos (180º) = -2.52*d J

Replacing in (1):

-15.6 J + 10.7*d J = -2.52*d J

Solving for d:

d = 1.18 m

7 0

3 years ago

A 7.0 mm -diameter copper ball is charged to 40 nC. What fraction of its electrons have been removed? The density of copper is 8

mylen [45]

Answer:

$f = 2.6 \times 10^{-13}$

Explanation:

Let the mass of copper ball is "m" gram

now the total number of copper atom present in the ball is given as

$N = \frac{m}{29} \times 6.02 \times 10^{23}$

now the total number of electrons in one copper atom is 29

so total number of electrons in given sample of copper ball is

$N_e = m(6.02 \times 10^{29})$

now diameter of the ball is 7.0 mm

density of the ball = $8900 kg/m^3$

now we have

$m = (\frac{4}{3}\pi r^3)(8900)$

$m = (\frac{4}{3}\pi(\frac{0.007}{2})^3)(8900)$

$m = 1.6 gram$

now we have

$N_e = 9.63 \times 10^{23}$

now the charge on the copper ball is 40 nC

so the number of electrons removed

$Q = ne$

$40 \times 10^{-9} = n(1.6 \times 10^{-19}$

$n = 2.5 \times 10^{11}$

so the fraction of number of electrons removed is given as

$f = \frac{n}{N_e}$

$f = \frac{2.5 \times 10^{11}}{9.63 \times 10^{23}}$

$f = 2.6 \times 10^{-13}$

7 0

3 years ago

The resistances of two bulbs are in ratio 2:3 .The bulbs are connected in series across a battery. Find the ratio of powers in t

Deffense [45]

$\sf \huge \red{Answer : - }$

Ratio of resistances of two bulbs = 2:3

Both are connected in series.

We have to find the ratio of powers in the bulbs..

We know that, current flow through each conductor in series connection remains same. So, we have to use that formula of power which shows relation between current and resistance.

P = I² × R

For series connection; P ∝ R

→ P₁/P₂ = R₁/R₂

→ P₁/P₂ = 2/3

→ P₁ : P₂ = 2 : 3

3 0

4 years ago