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3 years ago

Which of the following substances are NOT formed by chemical bonds?

Physics

2 answers:

MAVERICK [17]3 years ago

8 0

Pure substance becuase if it is pure it is not a bond

Step2247 [10]3 years ago

3 0

Answer:

The answer is D. pure substance.

Explanation:

A pure substance is a particular class of homogeneous matter whose composition is fixed and chemically defined, that is, it has a stable chemical composition since it is a matter that remains chemically unaltered in its different states of aggregation, endowed with properties singular and characteristic. A pure substance is composed of entities such as molecules, formular units and atoms.

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A playground is on the flat roof of a city school, 6.2m above the street below. The vertical wall of the building is h=7.30m hig

olya-2409 [2.1K]

Answer:

a. 18.13m/s

b. 0.84m

c. 2.4m

Explanation:

a. to find the speed at which the ball was lunched, we use the horizontal component.Since the point distance from the base of the ball is 24m and it takes 2.20 secs to reach the wall,we can say that

t=distance /speed

$speed v_{x}=vcos\alpha=24/2.2=10.9m/s\\V=10.9/cos53^{0}\\V=18.13m/s$

Hence the speed at which ball was lunched is 18.13m/s

b. from the equation

$y=v_{y}t-\frac{1}{2}gt^{2}\\ v_{y}=18.13sin53=14.48m/s\\\\y=(14.48*2.2)-\frac{1}{2}9.8*2.2^{2}\\y=8.14m\\$

the vertical distance at which the ball clears the wall is

y=8.14-7.3=0.84m

c. the time it takes the ball to reach the 6.2m vertically

$6.2=14.47t-4.8t^{2}\\\\14.47t-4.8t^{2}-6.2=0\\\using\\t=-b±\frac{\sqrt{b^{2}-4ac} }{2a}\\ where \\a=-4.8, b=14.47t, c=6.2\\hence t=2.4secs$

the horizontal distance covered at this speed is

$y+24=(18.13cos53)2.4\\y=26.186-24\\y=2.12m$

4 0

3 years ago

After an eye examination, you put some eyedrops on your sensitive eyes. The cornea (the front part of the eye) has an index of r

mina [271]

Answer:

t = 103.45 n m

Explanation:

given,

refractive index of cornea = 1.38

refractive index of eye drop = 1.45

wavelength of refractive index = 600 nm

refractive index of eye drop is greater than refractive index of cornea and the air.

Formula used in this case

for constructive interference

$2 n t = (m + \dfrac{1}{2})\lambda$

At m = 0 for the minimum thickness, so

$2\times 1.45 \times t = (0 + 0.5)\times 600$

$2.9 \times t =300$

$t =\dfrac{300}{2.9}$

t = 103.45 n m

the minimum thickness of the film of eyedrops t = 103.45 n m

6 0

3 years ago

A soft drink (mostly water) flows in a pipe at a beverage plant with a mass flow rate that would fill 220 0.355 - L cans per min

jekas [21]

Answer:

a) 1.301 kg/s

b) 0.001301 m³/s

c) V₁ = 6.505 m/s, V₂ = 1.626 m/s

d) 118.93 kPa

Explanation:

Given:

The number of cans = 220

The volume of can, V = 0.355 L = 0.355 × 10⁻³ m³

time = 1 minute = 60 seconds

gauge pressure at point 2, P₂ = 152 kPa

b) Thus, the volume flow rate, Q = Volume/ time

Q = (220 × 0.355 × 10⁻³)/60 = 0.001301 m³/s

a) mass flow rate = Volume flow rate × density

since it is mostly water, thus density of the drink = 1000 kg/m³

thus,

mass flow rate = 0.001301 m³/s × 1000 kg/m³ = 1.301 kg/s

c) Given:

Cross section at point 1 = 2.0 cm² = 2 × 10 ⁻⁴ m²

Cross section at point 2 = 8.0 cm² = 8 × 10 ⁻⁴ m²

also,

Q = Area × Velocity

thus, for point 1

0.001301 m³/s = 2 × 10 ⁻⁴ m² × velocity at point 1 (V₁)

V₁ = 6.505 m/s

for point 2

0.001301 m³/s = 8 × 10 ⁻⁴ m² × velocity at point 1 (V₂)

V₂ = 1.626 m/s

d) Applying the Bernoulli's theorem between the points 1 and 2 we have

$P_1+\rho gV_1 + \frac{\rho V_1^2}{2}=P_2+\rho gV_2 + \frac{\rho V_2^2}{2}$

$P_1=P_2+\rho\timesg(y_2-y_1)+\frac{\rho}{2}(V_2^2-V_1^2))$

on substituting the values in the above equation, we get

$P_1=152+1000\times 9.8(1.35)+\frac{1000}{2}(1.626^2-6.505^2))$

it is given that point 1 is above point 2 thus, y₂ -y₁ is negative

$P_1=118.93\ kPa$

thus, gauge pressure at point 1 is 118.93 kPa

8 0

3 years ago

The two forces acting on a skydiver are __________ and air _____________.

Stolb23 [73]

Answer:

Gravity and

Air resistance

Explanation:

The two forces acting on a skydiver are gravitational force and air resistance.

Gravitational force is a force that tends to pull all massive bodies towards the center of the earth. It works on all bodies that has mass. The larger or bigger the mass, the more the pull of gravity on the body.

Air resistance is the drag of air on a body as it passes to it. It is resisting force.

When a sky diver jumps out of a plane, he/she encounters both gravity and air resistance.
It soon balances both force and attain terminal velocity.
Air resistance is a frictional force that opposes motion.
This frictional force pushes in the opposite direction of motion
Motion direction is downward due to the celerity caused by gravity.

3 0

3 years ago

Read 2 more answers

What is power in physics

Shkiper50 [21]

Edit

In physics, power is the rate of doing work or of transferring heat, i.e. the amount of energy transferred or converted per unit time. Having no direction, it is a scalarquantity. In the International System of Units, the unit of power is the joule per second (J/s), known as the watt in honour of James Watt, the eighteenth-century developer of the condenser steam engine. Another common and traditional measure is horsepower (comparing to the power of a horse). Being the rate of work, the equation for power can be written:

Power

Common symbols

Derivations from

other quantities

P = E/t

P = F·v

P = V·I

P = T·ω

As a physical concept, power requires both a change in the physical system and a specified time in which the change occurs. This is distinct from the concept of work, which is only measured in terms of a net change in the state of the physical system. The same amount of work is done when carrying a load up a flight of stairs whether the person carrying it walks or runs, but more power is needed for running because the work is done in a shorter amount of time.

8 0

3 years ago