A car is traveling at 20 km in 15 minutes. What is its average velocity

What is x-rays ? and how it's formed ?

tia_tia [17]

X - rays are highly penetrating electromagnetic radiations that are formed when the cathode rays strikes a dense metal.

It has many characteristics such as :

bears no charge.

travels with the speed of light.

can ionize gases.

3 0

2 years ago

A copper rod of cross-sectional area 11.6 cm2 has one end immersed in boiling water and the other in an ice-water mixture, which

julia-pushkina [17]

Answer:

0.686 g of ice melts each second.

Solution:

As per the question:

Cross-sectional Area of the Copper Rod, A = $11.6\ cm^{2} = 11.6\times 10^{- 4}\ m^{2}$

Length of the rod, L = 19.6 cm = 0.196 m

Thermal conductivity of Copper, K = $390\ W/m.^{\circ}C$

Conduction of heat from the rod per second is given by:

$q = \frac{KA\Delta T}{L}$

where

$\Delta T = 100^{\circ} - 0^{\circ} = 100^{\circ}C$ = temperature difference between the two ends of the rod.

Thus

$q = \frac{390\times 11.6\times 10^{- 4}\times 100}{0.196} = 228.48\ J/s$

Now,

To calculate the mass, M of the ice melted per sec:

$M = \frac{q}{L_{w}}$

where

$L_{w}$ = Latent heat of fusion of water = 333 kJ/kg

$M = \frac{228.48}{333\times 10^{3}} = 6.86\times 10^{- 4}\ kg = 0.686\ g$

5 0

3 years ago

A mother pushes a baby stroller 10 meters by applying 40 newtons of force. how much work was done?

topjm [15]

Based on the situation above the the work done was 400 Joules. <span>Q = FS cos(theta) is the so-called work function. It's important to learn the work physics; you'll see it over and over in science/physics class. Theta is the angle between the force vector F and the distance vector S. In your problem we assume theta = 0, the two vectors were assumed aligned.</span>

7 0

3 years ago

Read 2 more answers

If you wanted to increase your muscular endurance, it would be important to participate in activities that __________.

Maurinko [17]

In order to increase muscular endurance, it is important to take part in activities that increase the size of muscle cells and the amount of blood that is delivered to the cells<span>. The increased size of the muscle cells reuires them to contract less to accomplish the same task; moreover, the increased blood flow helps deliver oxygen and nutrients to the blood.</span>

3 0

2 years ago

Read 2 more answers

A spacecraft is in a circular Earth orbit at an altitude of 6000 km . By how much will its altitude decrease if it moves to a ne

blagie [28]

Answer:

a) 2148 km = 2150 km

b) 840 km

Explanation:

The force keeping the satellite in circular motion is the force given by Netwon's gravitational law

Centripetal force = (mv²/r)

Force due to Newton's law of gravitation = (GMm/r²)

where m = mass of satellite

M = mass of the earth

G = Gravitational constant

v = velocity of the satellite

r = radius of circular orbit

(mv²/r) = (GMm/r²)

v² = (GM/r)

Meaning that the square of the velocity of orbit is inversely proportional to the radius of circular orbit. (Since G and M are constants)

v² = (k/r)

when v = v₀, r = 6000 + 6378 = 12,378 km (the radius of orbit = 6000 km + radius of the earth)

v₀² = (k/12,378)

K = 12378v₀²

When the velocity increases by 10%, v₁ = 1.1v₀, the square of the new velocity = (1.1v₀)² = 1.21v₀² and the new radius of orbit = r₁

1.21v₀² = (k/r₁)

r₁ = (k/1.21v₀²)

Recall, k = 12378v₀²

r₁ = 12378v₀² ÷ 1.21v₀² = 10,229.75 km

10,229.75 km = (10,229.75 - 6378) km altitude above the Earth's surface

New altitude of orbit = 3851.75 km

Decrease in altitude = 6000 - 3851.75 = 2148 km

b) The period of orbit is related to the radius of orbit through Kepler's Law

T² ∝ R³

T² = kR³

When the period of orbit is T₀, Radius of orbit = R₀ = (6000 + 6378) = 12378 km (Earth's radius = 6378 km)

T₀² = kR₀³

T₀² = k(12378)³

k = (T₀²) ÷ (12378)³

When the period reduces by 10%, T₁ = 0.90T₀ and the new radius of orbit = R₁

T₁² = kR₁³

(0.90T₀)² = kR₁³

0.81T₀² = kR₁³

R₁³ = (0.81T₀²) ÷ k

Recall, k = (T₀²)/(12378)³

R₁³ = (0.81T₀²) ÷ [(T₀²)/(12378)³]

R₁³ = 1,536,160,005,663.1

R₁ = ∛(1,536,160,005,663.1) = 11,538.4 km

New Altitude = R₁ - (Radius of the Earth)

= 11,538.4 - 6378 = 5160.4 km

Decrease in altitude = 6000 - 5160.4 = 839.6 km = 840 km

Hope this Helps!!!

3 0

3 years ago