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Marta_Voda [28]
3 years ago
6

A driver of a car traveling at 15.0 m/s applies the brakes, causing a uni- form acceleration of −2.0 m/s2 . How long does it tak

e the car to acceler- ate to a final speed of 10.0 m/s? How far has the car moved during the braking period?
Physics
1 answer:
Delicious77 [7]3 years ago
3 0

Answer:

It takes the car 2.5 s to slow down to a final speed of 10.0 m/s.

The car has moved 31.25 m during the braking period.

Explanation:

Assuming that motion is a straight line and knowing that the accelaration is a constant (-2.0 m/s²), these equations apply:

v(t) = v0 +a*t

X(t) = X0 + v0*t + 1/2*a*t²

where:

v(t) = velocity at time "t".

v0 = initial velocity.

a = acceleration.

t = time.

X(t) = position at time "t"

X0 = initial position

Given data:

v0 = 15.0 m/s

a = 2.0 m/s²

v(t) = 10.0 m/s

We need to find "t" at which the speed is 10 m/s.

From the equation of velocity above:

v(t) = v0 + a*t

solving the equation for "t"

v(t) - v0 = a*t

(v(t) - v0)/a = t

(10 m/s - 15 m/s) / (-2m/s²) = t

2.5 s = t

Now that we know how long it takes to slow down to a speed of 10 m/s, we can calculate how far has the car moved in that period using the equation for position at a given time:

X(t) = X0 + v0*t + 1/2*a*t²

Since we only want to know how many meters has the car moved during 2.5 s with an acceleration of -2m/s², we can make X0(initial position) = 0.

Then:

X(2.5 s) = 0 m + 15 m/s * 2.5 s + 1/2 * (-2m/s²)* (2.5 s)²

X(2.5 s) = 37.5 m + (-6.25 m) = 31.25 m

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A machine part has the shape of a solid uniform sphere of mass 220 g and diameter 4.50 cm . It is spinning about a frictionless
miss Akunina [59]

Answer:

The angular acceleration is 10.10 rad/s².

Explanation:

Given that,

Mass of sphere =220 g

Diameter = 4.50 cm

Friction force = 0.0200 N

Suppose we need to find its angular acceleration.

We need to calculate the angular acceleration

Using formula of torque

\tau=f\times r

I\times\alpha=f\times r

Here, I = moment of inertia of sphere

\dfrac{2}{5}mr^2\times\alpha=f\times r

\alpha=\dfrac{5\times f}{2mr}

Put the value into the formula

\alpha=\dfrac{5\times0.0200}{2\times220\times10^{-3}\times2.25\times10^{-2}}

\alpha=10.10\ rad/s^2

Hence, The angular acceleration is 10.10 rad/s².

7 0
3 years ago
A woman drives 200 miles west and then turns south and drives 375 miles. Her trip takes her 11.75 hrs. What is the woman's avera
FromTheMoon [43]

Answer:

The woman's average velocity during the trip is 36.2 miles/hour.

Explanation:

Velocity can be define as the displacement of an object per time. It is a vector quantity, and measured in m/s.

i.e velocity = \frac{displacement}{time}

From the given question,

Displacement = \sqrt{200^{2} + 375^{2}  }

                       = \sqrt{40000+140625}

                       = \sqrt{180625}

                       = 425

The displacement of woman is 425 miles.

velocity = \frac{425}{11.75}

             = 36.1702 miles/hour

The woman's average velocity during the trip is 36.2 miles/hour.

7 0
3 years ago
If you were designing a room in a house, where would be the better place to put a heater, near the floor or near the ceiling? Wh
taurus [48]

Answer: The correct explanation is 2.

Explanation: The warm air is less dense (it expands) and thus it is lighter than the cold air so it will rise up to the floor. Therefore, when you place the heater on the floor it will warm the cold air which would then rise and be replaced by more cold air which would again get warm and rise and so on until the room is heated. This means that the correct explanation is 2.

On the other hand, if you put the heater at the ceiling, it will warm the cold air near the ceiling which would stay up there (it is lighter than the cold air under it). This means that the only way for the heat to spread from this ceiling level warm air to the lower levels is via conduction which is slow.  

5 0
3 years ago
A dog runs 60 meters in 6 seconds. What is the average speed?
Ymorist [56]

Answer:

Distance =60m, Time = 6s, Speed = ?

Speed = distance/time

= 60/6

=10m/s

Explanation:

Hope that this is helpful.

Have a nice day.

8 0
3 years ago
Which describes the movement of a fluid during convection?
VikaD [51]
The movement of a fluid during convection is a circular/oval motion since the fluid at the top sinks and the fluid at the bottom rises.

Hope this helps :)
3 0
3 years ago
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