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3 years ago

Three out of four crashes happen at a speed of __________ miles per hour or less.

1 answer:

5 0

<span>The answer is 45 miles per hour or even less. Most crashes occur at a speed of 45 miles per hour or even less, and most of these accidents occur close to our homes. These crashes may also be caused by different factors, such as being drunk or sudden occurrences that are not controllable, which is why it is best to precede with caution when driving at crowded areas.</span>

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Mac and Keena are experimenting with pulses on a rope. Mac vibrates one end up and down while Keena holds the other end. This cr

Mariulka [41]

Mac and Keena are experimenting with pulses on a rope. Mac vibrates one end up and down while Keena holds the other end. This creates a pulse which they observe moving from end to end. How does the position of a point on the rope before the start of the pulse compare to its position after the pulse passes? Explain your reasoning.

4 0

2 years ago

The robot arm is elevating and extending simultaneously. At a given instant, θ = 30°, ˙ θ = 10 deg / s = constant θ˙=10 deg/s=co

motikmotik

Explanation:

The position vector r:

$\overrightarrow{r(t)}=lcos\theta\hat{i}+lsin\theta\hat{j}$

The velocity vector v:

$\overrightarrow{v(t)}=\overrightarrow{\frac{dr}{dt}}=\dot{l}cos\theta-lsin\theta\dot{\theta}\hat{i}+\dot{l}sin\theta+lcos\theta\dot{\theta}\hat{j}$

The acceleration vector a:

$\overrightarrow{a(t)}}=cos\theta(\ddot{l}-l\dot{\theta}^2)-sin\theta(2\dot{l}\dot{\theta}+l\ddot{\theta})\hat{i}+cos\theta(2\dot{l}\dot{\theta}+l\ddot{\theta})+sin\theta(\ddot{l}-l\dot{\theta}^2)\hat{j}$

$\overrightarrow{v(t)}=0.13\hat{i}+0.18\hat{j}$

$\overrightarrow{a(t)}}=-0.3\hat{i}-0.1\hat{j}$

5 0

2 years ago

For copper, ρ = 8.93 g/cm3 and M = 63.5 g/mol. Assuming one free electron per copper atom, what is the drift velocity of electro

viktelen [127]

Answer:

$V_d$ = 1.75 × 10⁻⁴ m/s

Explanation:

Given:

Density of copper, ρ = 8.93 g/cm³

mass, M = 63.5 g/mol

Radius of wire = 0.625 mm

Current, I = 3A

Area of the wire, $A = \frac{\pi d^2}{4}$ = $A = \frac{\pi 0.625^2}{4}$

Now,

The current density, J is given as

$J=\frac{I}{A}=\frac{3}{ \frac{\pi 0.625^2}{4}}$ = 2444619.925 A/mm²

now, the electron density, $n = \frac{\rho}{M}N_A$

where,

$N_A$ =Avogadro's Number

$n = \frac{8.93}{63.5}(6.2\times 10^{23})=8.719\times 10^{28}\ electrons/m^3$

Now,

the drift velocity, $V_d$

$V_d=\frac{J}{ne}$

where,

e = charge on electron = 1.6 × 10⁻¹⁹ C

thus,

$V_d=\frac{2444619.925}{8.719\times 10^{28}\times (1.6\times 10^{-19})e}$ = 1.75 × 10⁻⁴ m/s

4 0

3 years ago

Read 2 more answers

A skateboarder flies horizontally off a cement planter. After 3 seconds the skateboarder lands on the ground with a final veloci

evablogger [386]

Given the time, the final velocity and the acceleration, we can calculate the initial velocity using the kinematic equation A:

$v = v_o + a \Delta t$

A skateboarder flies horizontally off a cement planter. After a time of 3 seconds (Δt), he lands with a final velocity (v) of −4.5 m/s. Assuming the acceleration is -9.8 m/s² (a), we can calculate the initial velocity of the skateboarder (v₀) using the kinematic equation A.

$v = v_o + a \Delta t\\\\v_o = v - a \Delta t = (-4.5 m/s) - (-9.8 m/s^{2} ) \times 3 s = 24.9 m/s$

Given the time, the final velocity and the acceleration, we can calculate the initial velocity using the kinematic equation A:

$v = v_o + a \Delta t$

Learn more: brainly.com/question/4434106

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3 years ago

Which describes why nonrenewable energy resources are used more frequently than renewable ones?

vodomira [7]

They are inexpensive to use

5 0

3 years ago