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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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3 years ago
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In an electric shaver, the blade moves back and forth over a distance of 2.0 mm in simple harmonic motion, with frequency 124 Hz
bagirrra123 [75]

Answer:

(a) A = 1 mm

(b) V_{max}=0.77872 m/s

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V_{max}=778.72 \times 0.001

V_{max}=0.77872 m/s

(c) The formula for the maximum acceleration is given by

a_{max}=\omega ^{2}A

a_{max}=778.72 ^{2}\times 0.001

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8 0
3 years ago
) By observing that the centripetal acceleration of the Moon around the Earth is ac = 2.7 × 10-3 m/s2, what is the gravitatonal
Sedbober [7]

Answer:

G = 6,786 10⁻¹¹ m³ / s² kg

Explanation:

The law of universal gravitation is

         F = G m M/ r²

Where G is the gravitational constant, m and M are the masses of the bodies and r is the distance from their centers

Let's use Newton's second law

         F = m a

The acceleration is centripetal

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We replace

         G m M / r² = m  a_{c}  

         G =  a_{c}   r² / M

Let's replace and calculate

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[N m²/kg²] = [kg m/s²   m² / kg²] = [m³ / s² kg]

4 0
2 years ago
A 20-kg child starts at the center of a playground merry-go-round that has a radius of 1.5 mm and rotational inertia of 500kg⋅m2
Lemur [1.5K]

Answer:

w = 0.189 rad/ s

Explanation:

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Final

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Initial angular velocity

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Let's calculate

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3 years ago
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