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3 years ago

Find the initial velocity of a car which stops in 10sec, after applying brakes at the rate of 2m/s²

Physics

1 answer:

Dennis_Churaev [7]3 years ago

7 0

Answer:

$20\ m/s$

Explanation:

Since we are given time, acceleration, and final velocity, we can use the following formula to find the initial velocity:

$v_f = v_i + at$

Our given values:

$v_f = 0\\a = -2\\t = 10\\$

<em>Acceleration is negative because the car is slowing down.</em>

Add the values to the formula, and solve for $v_i$ :

$v_f = v_i + at\\0 = v_i + (-2)(10)\\0 = v_i -20\\20 = v_i$

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It takes about 20 seconds for a jet plane to go from rest to the takeoff speed of 100 mph (44.7 m/s). What is the average horizo

Ksju [112]

Answer:

Correct answer: F = 214.56 N

Explanation:

Given:

V₀ = 0 m/s initial speed

V = 44.7 m/s speed after t = 29 seconds

m = 96 kg

F = ? horizontal force

Taking off an airplane is a uniformly accelerated motion to which the formula applies:

V = V₀ + a t and V₀ = 0 m/s

V = a t ⇒ a = V / t = 44.7 / 20 = 2.235 m/s²

a = 2.235 m/s²

the horizontal force is calculated using the formula:

F = m · a = 96 · 2.235 = 214.56 N

F = 214.56 N

God is with you!!!

4 0

4 years ago

A violin string has a standard length of 32.8 cm. It sounds the musical note A (440 Hz) when played without fingering. How far f

Rus_ich [418]

Answer:

The finger has to be placed at 5.25cm

Explanation:

The steps and appropriate formula in musical instrument is as shown in the attachment.

5 0

3 years ago

If Hubble's constant is 73 km/s/Mpc then the age of the universe is 13.4 billion years, assuming a uniform expansion. Suppose it

ki77a [65]

Answer:

It would decrease the calculated age of the universe

Explanation:

Since the age of the universe is the reciprocal of Hubble's constant, it's therefore if Hubble's constant is increased the age decreases but if the Hubble's constant is decreased, the age of universe increases. Therefore, the age of universe and Hubble's constant are inversely proportional. Conclusively, any attempt to increase Hubble's constant would imply the calculated age of the universe decreases.

3 0

3 years ago

A mercury barometer reads 745.0 mm on the roof of a building and 760.0 mm on the ground. Assuming a constant value of 1.29 kg/m3

Ipatiy [6.2K]

Answer:

The height of the building is 158.140 meters.

Explanation:

A barometer is system that helps measuring atmospheric pressure. Manometric pressure is the difference between total and atmospheric pressures. Manometric pressure difference is directly proportional to fluid density and height difference. That is:

$\Delta P \propto \rho \cdot \Delta h$

$\Delta P = k \cdot \rho \cdot \Delta h$

Where:

$\Delta P$ - Manometric pressure difference, measured in kilopascals.

$\rho$ - Fluid density, measured in kilograms per cubic meter.

$\Delta h$ - Height difference, measured in meters.

Now, an equivalent height difference with a different fluid can be found by eliminating manometric pressure and proportionality constant:

$\rho_{air} \cdot \Delta h_{air} = \rho_{Hg} \cdot \Delta h_{Hg}$

$\Delta h_{air} = \frac{\rho_{Hg}}{\rho_{air}} \cdot \Delta h_{Hg}$

Where:

$\Delta h_{air}$ - Height difference of the air column, measured in meters.

$\Delta h_{Hg}$ - Height difference of the mercury column, measured in meters.

$\rho_{air}$ - Density of air, measured in kilograms per cubic meter.

$\rho_{Hg}$ - Density of mercury, measured in kilograms per cubic meter.

If $\Delta h_{Hg} = 0.015\,m$ , $\rho_{air} = 1.29\,\frac{kg}{m^{3}}$ and $\rho_{Hg} = 13600\,\frac{kg}{m^{3}}$ , the height difference of the air column is: