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hjlf
4 years ago
6

A car starts from rest and after 7 seconds it is moving at 42 m/s. What is the car’s average acceleration? A. 0.17 m/s2 B. 1.67

m/s2 C. 6 m/s2 D. 7 m/s2 E. none of the above
Physics
2 answers:
aliya0001 [1]4 years ago
5 0
Acceleration =velocity /time
=42/7
=6
tamaranim1 [39]4 years ago
4 0

C. 6 m/s2 is correct

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As keisha runs the generator, which best describes what should happen to the needle that measures electric current? it will move
SOVA2 [1]

The diagram shows a simple electric generator. The needle that measures electric current will move back and forth between a largely positive and a large negative value.

  • What is an electric generator?
  1. An electric generator is physically equivalent to an electric motor. but it converts mechanical energy into electrical energy.
  2. The electrical field generated is dependent on the inclination of the wire with respect to magnetic field lines, and this inclination changes over time,

because of that she will experience a varying electrical field, and thus a varying electric current will be zero.

The maximum positive value will occur when the wire is perpendicular to the magnetic field lines after one-fourth of rotation, and then zero.

Hence option C is correct.

The diagram shows a simple electric generator. The needle that measures electric current will move back and forth between a largely positive and a large negative value.

 

Learn more about electric generator here:

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2 years ago
A scientist is trying to predict the regions of the world most likely to see a decrease in natural resources from population cha
aleksley [76]

<u><em>Developed countries will see a decrease in natural resources, because their population will decrease.</em></u>

8 0
3 years ago
Read 2 more answers
Select the correct answer.
spin [16.1K]

Answer:

There isnt enough in your question to answer the question bro, like we need a picture or something bro.

Explanation:

7 0
3 years ago
A 2.0 µF capacitor is charged through a 50,000 ohm resistor. How long does it take for the capacitor to reach 90% of full charge
Nesterboy [21]

Answer:

0.23 s

Explanation:

First of all, let's find the time constant of the circuit:

\tau=RC

where

R=50,000 \Omega is the resistance

C=2.0\mu F=2.0\cdot 10^{-6}F is the capacitance

Substituting,

\tau=(50,000 \Omega)(2.0\cdot 10^{-6}F)=0.1 s

The charge on a charging capacitor is given by

Q(t)=Q_0 (1-e^{-t/\tau} ) (1)

where

Q_0 is the full charge

we want to find the time t at which the capacitor reaches 90% of the full charge, so the time t at which

Q(t)=0.90 Q_0

Substituting this into eq.(1) we find

0.90 Q_0 = Q_0 (1-e^{-t/\tau})\\0.90=1-e^{-t/\tau}\\e^{-t/\tau}=1-0.90=0.10\\-\frac{t}{\tau}=ln(0.10)\\t=-\tau ln(0.10)=(0.1 s)ln(0.10)=0.23 s

4 0
3 years ago
A small metal bar whose initial temperature was 20 degrees Celsius is dropped into a large container of boiling water. How long
Vesnalui [34]
Below is the answer. I hope it help.
T ( t ) = C e k t + T m where Tm is the temperature of the surroundings 
T ( t ) = C e k t + T m
T ( 0 ) = 20
T ( 1 ) = T ( 0 ) + 2 = 22
C + T m = 20 C+Tm=20 
C e k + T m = 22

4 0
3 years ago
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