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A plane is landing. It started at 400m/s and ended up at 50m/s after 30 seconds. What is it's acceleration?

quester [9]

Give u = start velocity

v = end velocity

v = u + at

50 = 400 + a*30

30a = -350

a = -116.67 m/ $s^{2}$

**Why the accecleration is negative number**

Because displacement, velocity, and acceleration are VECTOR QUANTITIES.

Vector Quantity must have direction.

4 0

3 years ago

How do i do this question？just number 5

larisa86 [58]

5 a)

Start by arranging the materials by the sonic speed and then their physical state:

$4600 \; \text{m} \cdot \text{s}^{-1}$ - Copper (solid)
$4500 \; \text{m} \cdot \text{s}^{-1}$ - Glass (solid)
$4000 \; \text{m} \cdot \text{s}^{-1}$ - Wood (solid)

$1500 \; \text{m} \cdot \text{s}^{-1}$ - Sea Water (liquid)
$1200 \; \text{m} \cdot \text{s}^{-1}$ - Acetone (liquid)
$1100 \; \text{m} \cdot \text{s}^{-1}$ - Alcohol (liquid)

$972 \; \text{m} \cdot \text{s}^{-1}$ - Helium (gas)
$267 \; \text{m} \cdot \text{s}^{-1}$ - Carbon dioxide (gas)

What trend do you identify from these data? Here's what I've got:

$\text{Sonic Speed}: \text{solid} > \text{liquid} > \text{gas}$

5 b)

The way microscopic particles are arranged in a substance helps distinguish between different physical states:

Particles in a solid are held tightly in place with small separation in between; it's hard for particles in a solid to move past one another; solids therefore have shapes that persists over time.
Particles in a gas are highly mobile- they keep moving AT ALL TIMES. There are large separations between individual particles and therefore gases tend to show no definite shape or volume.
The arrangement of particles in a liquid is located somewhere in between that of solids and gases. The exact configuration is dependent on the nature of the liquid- for example, molecules in maple syrup are held way closer to each other than those in distilled water are.

Sound travels as a longitudinal wave. As a sound wave passes through a medium, individual particles become excited and gain energy; as they run into others they transfer their energy to the next particle; the sound wave thus propagate across the medium. With a lower average distance between individual particles this action can proceed at a greater rate in average solids than in average liquids, and in average liquids than in average gases. Hence the trend.

3 0

3 years ago

A baseball pitcher throws the ball in a motion where there is rotation of the forearm about the elbow joint as well as other mov

vovikov84 [41]

Answer:

364.4 J

Explanation:

I = Moment of inertia of the forearm = 0.550 kgm²

v = linear velocity of the ball relative to elbow joint = 17.1 m/s

r = distance from the joint = 0.470 m

w = angular velocity

Using the equation

v = r w

17.1 = (0.470) w

w = 36.4 rad/s

Rotational kinetic energy of the forearm is given as

RKE = (0.5) I w²

RKE = (0.5) (0.550) (36.4)²

RKE = 364.4 J

4 0

4 years ago

Read 2 more answers

#1 What materials is each part of the flashlight made of? (A flashlight will include wires,a light bulb,a lens, a reflector ,and

s344n2d4d5 [400]

Explanation:

Question 1

1.The wires are made of conducting materials e.g copper

2. A light bulb is made of filament material e.g tungsten with gases enclosed in a glass material

3.The lens is made of transparent glass material

4 The reflector is made of plastic with silver lining

5. The exterior casing of most flash lights are made of plastic

Question 2.

1.Copper is used to conduct electric current from the battery to the bulb

2.The tungsten filament ignite the gases and causes it to glow

3. The lens covers the lamp on your flashlight so that the glass on the lamp

/bulbs does not get broken.

4.The reflector redirects the light rays from the lamp, creating a steady beam of light, which is the light you see emitting from the flashlight.

5. The exterior cases houses the entire assembly and makes the flash light handy for use

4 0

3 years ago

The maximum wavelength that an electromagnetic wave can have and still eject electrons from a metal surface is 542 nm. What is t

Veseljchak [2.6K]

Answer:

2.295 eV

Explanation:

maximum wavelength, λ = 542 nm = 542 x 10^-9 m

The work function of the metal is defined as the minimum amount of energy falling on the metal so that the photo electrons just ejects the surface of metal.

$W_{o}=\frac{hc}{\lambda }$

where, h is the Plank's constant and c be the speed of light

h = 6.634 x 10^-34 Js

c = 3 x 10^8 m/s

$W_{o}=\frac{6.634\times 10^{-34}\times 3\times 10^{8}}{542\times10^{-9} }$

$W_{o}=3.67\times 10^{-19} J=\frac{3.67\times 10^{-19}}{1.6\times 10^{-19}} eV$

Wo = 2.295 eV

Thus, the work function of this metal is 2.295 eV.

5 0

3 years ago