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2 years ago

If a car accelerates from rest at a constant 4 m/s

Physics

1 answer:

Readme [11.4K]2 years ago

4 0

Answer:

The time it will take for the car to reach a velocity of 28 m/s is 7 seconds

Explanation:

The parameters of the car are;

The acceleration of the car, a = 4 m/s²

The final velocity of the car, v = 28 m/s

The initial velocity of the car, u = 0 m/s (The car starts from rest)

The kinematic equation that can be used for finding (the time) how long it will take for the car to reach a velocity of 28 m/s is given as follows;

v = u + a·t

Where;

v = The final velocity of the car, v = 28 m/s

u = The initial velocity of the car = 0 m/s

a = The acceleration of the car = 4 m/s²

t = =The time it will take for the car to reach a velocity of 28 m/s

Therefore, we get;

t = (v - u)/a

t = (28 m/s - 0 m/s)/(4 m/s²) = 7 s

The time it will take for the car to reach a velocity of 28 m/s, t = 7 seconds.

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1 year ago

The minimum stopping distance of a car moving at 20.5 mi/h is 11.6 m. Under the same conditions (so that the maximum braking for

pshichka [43]

Answer:

d = 69 .57 meter

Explanation:

First case

Speed of car ( v ) = 20.5 mi/h = 9.164 M/S

distance ( d ) = 11.6 meter ( m = mass of the car )

Work done = 0.5 m v² = 0.5 * 9.164² * m J = 41.99 m J

Force = ( workdone /distance ) = ( 41.99 m / 11.6 ) = 3.619 m N

Second case

v = 50.2 mi/h = 22.44135 m/s

d = ?

Work done = 0.5 * 22.44² * m J = 251.7768 * m J

Since the braking force remains the same .

3.619 m = ( 251.7768 m / d )

d = 69 .57 meter

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2 years ago

"A boat that can travel at 4.0 km/h in still water crosses a river with a current of 2.0 km/h. At what angle must the boat be po

IRISSAK [1]

Answer:

30 degrees

Explanation:

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2 years ago

You kick a soccer ball off the ground with a velocity of 15 m/s at an angle of 40° above the horizontal

jeyben [28]

At its maximum height, the ball will have zero vertical velocity, so the ball's velocity at this point is exactly equal to its horizontal velocity.

At any time t, the horizontal component of its velocity is

v = (15 m/s) cos(40°) ≈ 11.49 m/s

so at the highest point of its trajectory, the ball has a velocity of about 11.49 m/s pointed in the positive horizontal direction.

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2 years ago

Beginning 145 miles directly south of the city of Hartville, a car travels due west. If the car is travelling at a speed of 42 m

ziro4ka [17]

Answer:

The rate of change of the distance is 14.89.

Explanation:

Given that,

Distance = 145 miles

Speed of car = 42 miles/hr

Distance covered by car = 55 miles

We need to calculate the the rate of change of the distance

According to figure,

Let OA is x, and AB is y.

Now, using Pythagorean theorem

$x^2=y^2+145^2$

On differentiating

$2x\dfrac{dx}{dt}=2y\dfrac{dy}{dt}$

$\dfrac{dx}{dt}=\dfrac{y}{x}\dfrac{dy}{dt}$

$\dfrac{dx}{dt}=\dfrac{55\times42}{\sqrt{55^2+145^2}}$

$\dfrac{dx}{dt}=14.89\ miles/hr$

Hence, The rate of change of the distance is 14.89.

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2 years ago