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DochEvi [55]
3 years ago
10

8. A car travels at a constant velocity of 70 mph for one hour. By the end of the second hour, the car’s velocity was 60 mph. At

the end of the third hour, the car’s velocity was 80 mph. During which hour was their acceleration positive? During which hour was their acceleration negative?
Physics
1 answer:
Mrac [35]3 years ago
8 0

<u>Answer:</u>

  Positive acceleration is in third hour and negative acceleration is in second hour.

<u>Explanation:</u>

  Velocity of car in first hour =  70 mph

  Velocity of car in second hour = 60 mph

  Velocity of car in third hour = 80 mph

   Acceleration = Change in velocity / Time

   Acceleration in second hour = (60 - 70)/1 = -10 mph²

   Acceleration in third hour = (80 - 60)/1 = 20 mph²

   So positive acceleration is in third hour and negative acceleration is in second hour.

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A car traveled 1025 km from El Paso to Dallas iin 13.5 hr. What was its average velocity
JulsSmile [24]
1) 1025km per 13.5hr = 1025km/13.5hr = 75.9 km/hr

2) 400km per 30min = 400km/30min = 13.3 km/min
13.3km/min X (60min per hr) = 13.3km/min(60min/hr) = 800km/hr

3) 45km/hr in 40min = 45km/hr X 40min X (1hr/60min) = 30km.

<span> 4) (30m/s - 10m/s) per 10s = 20m/s/10s = 2ms/s = 2m/s/s = 2m/s^2 </span>
5 0
3 years ago
1) For a positive point charge, the lines radiate ………. . While, for a negative point charge, the lines converge …………. .
ch4aika [34]

Answer:

For a positive point charge, the lines radiate <u>outwards</u>, while for a negative point charge, the lines converge<u> inwards.</u>

Explanation:

A single point charges produces an electric field which has a radial shape.The sign of a charge determines the the direction of the field. In Positive charge have the direction of field is out of the charge and for negative charge, the direction of field is towards the charge.This behavior is in relation to how a positive test charge will experience in a field.

5 0
3 years ago
PLEASE HELP GIVING BRAINLIEST ANSWER
Rasek [7]
Potential energy is an object’s stored energy when it is not moving. Kinetic energy is an object’s energy in motion. You can’t be both moving and not moving at the same time, so PE and KE cannot be equal.
7 0
3 years ago
Two inductors, L1 and L2, are in parallel. L1 has a value of 25 mH and L2 a value of 50 mH. The parallel combination is in serie
Bond [772]

Answer:

Explanation:

For parallel inductors ,

\frac{1}{L_R} = \frac{1}{L_1} +\frac{1}{L_2}

\frac{1}{L_R} =\frac{1}{25} +\frac{1}{50}

L_R=16.67 mH.

For series combination

Total inductance

= 16.67 + 20

= 36.67 mH .

reactance of total inductance at 300 kHz

= ωL_{total} where ω is angular frequency

= 2πfL_{total}

= 2 x 3.14 x 300 x 10³ x 36.67 x 10⁻³

= 69.1 x 10³ ohm

Total rms current = Vrms / reactance

= 60 / 69.1 x 10³ A

= .87 x 10⁻³ A

= .87 mA

7 0
2 years ago
Physics - Electricity and Magnetism
Orlov [11]

Answer:

<h2>480</h2>

Explanation:

<h2>R=120÷0.25</h2><h2>R=480 ohms </h2>

because the unit for resistance is in ohms

4 0
2 years ago
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