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Lunna [17]
3 years ago
10

2. A race car starts at 400 m/s and then stops in 20 seconds. Calculate acceleration. Acceleration=final velocity - initial velo

city/ change in time
A. -20 m/s2
B. 40 m/s2
C. 20 m/s2
D. 55 m/s2
Physics
1 answer:
Nostrana [21]3 years ago
5 0
It is -20m/s2
400-0
————- = -20
20
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F. If the shuttle's period is synchronized with that of Earth's rotation, what is the height of the shuttle? (1 day = 8.64x104s,
oee [108]

Answer:

1.324 × 10⁷ m

Explanation:

The centripetal acceleration, a at that height above the earth equal the acceleration due to gravity, g' at that height, h.

Let R be the radius of the orbit where R = RE + h, RE = radius of earth = 6.4 × 10⁶ m.

We know a = Rω² and g' = GME/R² where ω = angular speed = 2π/T where T = period of rotation = 1 day = 8.64 × 10⁴s (since the shuttle's period is synchronized with that of the Earth's rotation), G = gravitational constant = 6.67 × 10⁻¹¹ Nm²/kg², ME = mass of earth = 6 × 10²⁴ kg. Since a = g', we have

Rω² = GME/R²

R(2π/T)² = GME/R²

R³ = GME(T/2π)²

R = ∛(GME)(T/2π)²

RE + h = ∛(GMET²/4π²)

h = ∛(GMET²/4π²) - RE

substituting the values of the variables, we have

h = ∛(6.67 × 10⁻¹¹ Nm²/kg² × 6 × 10²⁴ kg × (8.64 × 10⁴s)²/4π²) - 6.4 × 10⁶ m

h = ∛(2,987,477 × 10²⁰/4π² Nm²s²/kg) - 6.4 × 10⁶ m

h = ∛75.67 × 10²⁰ m³ - 6.4 × 10⁶ m

h = ∛(7567 × 10¹⁸ m³) - 6.4 × 10⁶ m

h = 19.64 × 10⁶ m - 6.4 × 10⁶ m

h = 13.24 × 10⁶ m

h = 1.324 × 10⁷ m

3 0
3 years ago
A car traveling with 500,000 J of kinetic energy is brought to a kinetic energy of
allsm [11]

Answer:

33,333.33 N

Explanation:

Given that :

Initial kinetic energy = 500,000 J

Final kinetic energy = 100,000 J

Using the relation :

Force * time = change in momentum (Newton's law)

Force (F) * 0.12 = (500,000 - 100,000)

0.12F = 400,000 J

Force = (400,000 J) / 0.12s

Force = 33333.333

Force = 33,333.33 N

3 0
3 years ago
An object that is accelerating may be
Elenna [48]

It must be either speeding up, or slowing down, or turning. There are no other possibilities.

6 0
3 years ago
A 20.0 Ω, 15.0 Ω, and 7.00 Ω resistor are connected in parallel to an emf source. A current of 7.00 A is in the 15.0 Ω resistor.
Lady bird [3.3K]

PART A)

Equivalent resistance in parallel is given as

\frac{1}{R} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}

now we have

\frac{1}{R} = \frac{1}{20} + \frac{1}{15} + \frac{1}{7}

R = 3.85 ohm

PART B)

since potential difference across all resistance will remain same as all are in parallel

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V = iR

As we know i = 7 A current flows through 15 ohm resistance

V = (7 A)(15 ohm) = 105 volts

PART C)

Similarly ohm's law for 20 ohm resistance we can say

V = iR

105 = i(20 ohm)

i = 5.25 A

3 0
4 years ago
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He was the first to improve the telescope i believe 
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3 years ago
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