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m_a_m_a [10]
3 years ago
14

A driver of a car traveling at -15m/s applies the brakes, causing a uniform acceleration of +2.0m/s2. If the brakes are applied

for 2.5s, what is the velocity of the car at the end of the braking period? How far has the car moved during the braking period?
Physics
1 answer:
klemol [59]3 years ago
3 0

Given :

Initial velocity, u = -15 m/s.

Acceleration , a = 2 m/s².

Time taken to applied brake, t = 2.5 s.

To Find :

The velocity of the car at the end of the braking period.

How far has the car moved during the braking period.

Solution :

By equation :

v = u+at\\\\v=-15 + 2\times 2.5\\\\v=-10 \ m/s

Now, distance covered by car is :

s=ut+\dfrac{at^2}{2}\\\\s=(-15)(2.5)+\dfrac{2(2.5)^2}{2}\\\\s=-31.25\ m

Hence, this is the required solution.

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By what factor is the self-inductance of an air solenoid changed if its length and number of coil turns are both tripled
fredd [130]

Answer:

The new self inductance is 3 times of the initial self inductance.

Explanation:

The self inductance of a solenoid is given by :

L=\dfrac{\mu_oN^2 A}{L}

Where

N is number of turns per unit length

A is area of cross section

l is length of solenoid

If length and number of coil turns are both tripled,

l' = 3l and N' = 3N

New self inductance is given by :

L'=\dfrac{\mu_oN'^2 A}{L'}\\\\=\dfrac{\mu_o(3N)^2 A}{3L}\\\\=3\dfrac{\mu_oN^2 A}{L}\\\\=3L

So, the new self inductance is 3 times of the initial self inductance.

4 0
3 years ago
Nasa’s goal is to help industry reduce emissions from aircraft by how much by 2050 compared to 2005?
lys-0071 [83]

Answer:

50%

Explanation:

Commercial aviation is responsible for 2% of global carbon emission. In the year 2009, the members of IATA (International Air Transport Association) had drawn a pledge to:

1. Halve the carbon emission due to aircraft by 2050, relative to emission of 2005

2. To make growth of industry carbon neutral by 2020

3. To cut CO₂ emission by 1.5% per year till 2020

To achieve these targets, a four pillar action plan was created.

8 0
3 years ago
Air contained in a rigid, insulated tank fitted with a paddle wheel, initially at 300 K, 2 bar, and a volume of 3 m3, is stirred
madam [21]

Answer:

a)P₂ =4 bar

b)W= - 1482.48 KJ

It means that work done on the system.

c)S₂ - S₁ = 3.42 KJ/K

Explanation:

Given that

T₁ = 300 K   ,V₁ = 3 m³  ,P₁=2 bar

T₂ = 600 K ,V₂=V₁ 3 m³

Given that tank is rigid and insulated.It means that volume of the gas will remain constant.

Lets take the final pressure = P₂

For ideal gas  P V = m R T

\dfrac{P_2}{P_1}=\dfrac{T_2}{T_1}

P_2=\dfrac{T_2}{T_1}\times P_1

P_2=\dfrac{600}{300}\times 2

P₂ =4 bar

Internal energy

ΔU = m Cv ΔT

Cv=0.71 KJ/kg.k for air

m=\dfrac{PV}{RT}

m=\dfrac{200\times 3}{0.287\times 300}\ kg

m= 6.96 kg

ΔU= 6.96 x 0.71 x (600 - 300)

ΔU=1482.48 KJ

From first law

Q= ΔU + W

Q= 0  Insulated

W = - ΔU

W= - 1482.48 KJ

It means that work done on the system.

Change in the entropy

S_2-S_1=mC_v\ \ln\dfrac{T_2}{T_1}

S_2-S_1=6.96\times 0.71\ \ln\dfrac{600}{300}

S₂ - S₁ = 3.42 KJ/K

 

5 0
3 years ago
Which of the following best explains why snow predictions by meteorologists are sometimes incorrect?
den301095 [7]

Answer:

C. Interference from the sun causes data to be collected inaccurately.

Explanation:

Snow predictions by meteorologists are sometimes incorrect because from the sun causes data to be collected inaccurately.

6 0
3 years ago
Convert 11 milliseconds into seconds
Alex17521 [72]

Answer:

0.011

Explanation:

6 0
3 years ago
Read 2 more answers
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