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3 years ago

(BRAINLIEST W/ WORK SHOWN!!!) Help with Physics question?

Physics

1 answer:

VashaNatasha [74]3 years ago

6 0

Answer:

$\boxed {3.43 x 10^{3}}$

Explanation:

We know that speed is defined as distance moved per unit time hence expressed as $v=\frac {d}{t}$ where v is speed in m/s, d is distance in m and t is time in seconds. Making d the subject of the above formula then

$d=vt$

Substituting 343 m/s for d and 10 s for t then

$d= 343\times10= 3430= 3.43 x 10^{3}$

Therefore, the distance between speaker and deter is $\boxed {3.43 x 10^{3}}$

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the jamaican bobsled team hit the brakes on their sled so that it decelerates at a uniform rate of 0.43 m/s, how long does it ta

IceJOKER [234]

here's a cheap trick
it would take the same time to accelerate from rest to top speed
as it would take to decelerate from top speed to zero
so
instead of
d = Vi t + 1/2 a t^2 where Vi is positive and a is negative
we'll use
Vi = 0 and a is positive
giving
85 = 0 + 1/2 (0.43) t^2 = 0.215 t^2
t^2 = 395.345
t = 19.88s or 20. s to 2 sig figs

or we ccould find Vi from
Vf*2 = Vi^2 + 2 a d
0 = Vi^2 + 2 (0.43) 85
Vi^2 = 71.4
Vi = 8.45m/s
then
85 = 8.45 t + 1/2 (-0.43) t^2
85 = 8.45 t - 0.215 t^2
0.215 t^2 - 8.45 + 85 = 0
t = 19.65s or 20. s to 2 s.f.(minor difference arises from rounding Vi)
or another cheap trick
when a is constant
Vavg = (Vf + Vi) /2 = 8.45/2 = 4.225
and
d = Vavg t
85 = 4.225 t
t = 20.12 or 20. s to 2 s.f. (minor differences from intermidiate roundings)

anyway you choose you get 20. s

4 0

3 years ago

How many miles will be completed by a runner with a constant speed of 5 mph in 30 minutes?

Mrac [35]

Distance=speed times time
speed=5mph=5 $\frac{mi}{hr}$
time=30mins=30/60hr=1/2hr

so
distance=speed times time
$distance=(5\frac{mi}{hr})(\frac{1}{2}hr)$
$distance=\frac{5mi \space\ hr}{2hr}$
$distance=2.5mi$

he will run 2.5 miles in 30 mins at the speed of 5mph

5 0

3 years ago

You're driving down the highway late one night at 20 m/s when a deer steps onto the road 39 m in front of you. Your reaction tim

miss Akunina [59]

Answer:

a) 10.8 m

b) 24.3 m/s

Explanation:

In order to get the total distance traveled since you see the deer till the car comes to an stop, we need to take into account that this distance will be composed of two parts.
The first one, is the distance traveled at a constant speed, before stepping on the brakes, which lasted the same time that the reaction time, i.e., 0.5 sec.
We can find this distance simply applying the definition of average velocity, as follows:

$\Delta x_{1} = v_{1o} * t_{react} = 20 m/s * 0.5 s = 10 m (1)$

The second part, is the distance traveled while decelerating at -11 m/s2, from 20 m/s to 0.
We can find this part using the following kinematic equation (assuming that the deceleration keeps the same all time):

$v_{1f} ^{2} - v_{1o} ^{2} = 2* a* \Delta x (2)$

where v₁f = 0, v₁₀ = 20 m/s, a = -11 m/s².
Solving for Δx, we get:

$\Delta x_{2} = \frac{-(20m/s)^{2}}{2*(-11m/s)} = 18.2 m (3)$

So, the total distance traveled was the sum of (1) and (3):
Δx = Δx₁ + Δx₂ = 10 m + 18.2 m = 28.2 m (4)
Since the initial distance between the car and the deer was 39 m, after travelling 28.2 m, the car was at 10.8 m from the deer when it came to a complete stop.

We need to find the maximum speed, taking into account, that in the same way that in a) we will have some distance traveled at a constant speed, and another distance traveled while decelerating.
The difference, in this case, is that the total distance must be the same initial distance between the car and the deer, 39 m.
⇒Δx = Δx₁ + Δx₂ = 39 m. (5)
Δx₁, is the distance traveled at a constant speed during the reaction time, so we can express it as follows:

$\Delta x_{1} = v_{omax} * t_{react} = 0.5* v_{omax} (6)$

Δx₂, is the distance traveled while decelerating, and can be obtained using (2):

$v_{omax} ^{2} = 2* a* \Delta x_{2} (7)$

Solving for Δx₂, we get:

$\Delta x_{2} = \frac{-v_{omax} ^{2} x}{2*a} = \frac{-v_{omax} ^{2}}{(-22m/s2)} (8)$

Replacing (6) and (8) in (5), we get a quadratic equation with v₀max as the unknown.
Taking the positive root in the quadratic formula, we get the following value for vomax:
v₀max = 24.3 m/s.

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3 years ago

What were the four pieces of evidence Alfred Wegener found to support his hypothesis about pangea?

sasho [114]

1 Same fossil in diff area

2 plate techtonics

3 same soil in diff area

4 they all fit like a giant puzzle

5 0

4 years ago

Check all that apply. An ammeter is used to measure current. An ammeter must be placed in parallel with a resistor to measure th

Juliette [100K]

Out of all given choices, the following statements are true:

An ammeter is used to measure current.
A voltmeter is used to measure voltage.
A voltmeter must be placed in parallel with a resistor to measure the voltage across the resistor.

Options A, E, and F

Explanation:

An instrument by which the current in a circuit is measured is called ammeter whereas an instrument in which voltage is measured in a circuit is called a voltmeter . The ammeter is placed in series with the resistor while the voltmeter is placed in parallel with the resistor.

For the option B, since the ammeter must be placed in series with the resistor to measure current, it is false. Option C is false because an ammeter has zero internal resistance. Option D is also false because a voltmeter has a high internal resistance and is actually infinite.

6 0

3 years ago