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4 years ago

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The elevators in the Landmark Tower in Yokohama, Japan are among the fastest in the world. After starting from rest, they reach

a maximum speed of 120 meters per minute. It takes the elevator 4.0 seconds to reach maximum speed. What is its acceleration in m/s/s (meters per second per second)?

1 answer:

MariettaO [177]4 years ago

3 0

Answer:

The acceleration is 30 m/s²

Explanation:

Given that,

Maximum speed = 120 m/s

Time = 4.0 sec

We need to calculate the acceleration

Using equation of motion

$v=u+at$

Where, v = speed

u = initial speed

a = acceleration

t = time

Put the value into the formula

$120=0+a\times4.0$

$a=\dfrac{120}{4.0}$

$a=30\ m/s^2$

Hence, The acceleration is 30 m/s²

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An airplane pilot wishes to fly directly westward. According to the weather bureau, a wind of 75.0 km/hour is blowing southward.

Alex17521 [72]

Answer:

The speed of the plane relative to the ground is 300.79 km/h.

Explanation:

Given that,

Speed of wind = 75.0 km/hr

Speed of plane relative to the air = 310 km/hr

Suppose, determine the speed of the plane relative to the ground

We need to calculate the angle

Using formula of angle

$\sin\theta=\dfrac{v'}{v}$

Where, v'=speed of wind

v= speed of plane

Put the value into the formula

$\sin\theta=\dfrac{75}{310}$

$\theta=\sin^{-1}(\dfrac{75}{310})$

$\theta=14.0^{\circ}$

We need to calculate the resultant speed

Using formula of resultant speed

$\cos\theta=\dfrac{v''}{v}$

Put the value into the formula

$\cos14=\dfrac{v''}{310}$

$v''=\cos14\times310$

$v''=300.79\ km/h$

Hence, The speed of the plane relative to the ground is 300.79 km/h.

6 0

3 years ago

A car starts from rest with an acceleration of 6

mrs_skeptik [129]

Answer:

$t=16.67s$

Explanation:

From the question, acceleration from $6m/s^2 \ to \ 0m/s^2$ in 10 seconds.

Acceleration function can be written as:-

$a_t=6-0.6t$

From the acceleration equation, we can obtain the velocity equation:

$v(t)=\int\limits^t_b {0} \, dv=\int\limits^t_0 {a(t)} \, dt\\v(t)=\int\limits^t_0 {(6-06t)} \, dt=6t-0.3t^2\\*dv=a(t)dt$

We calculate velocity after 10sec from the above v(t) as $30m/s$ .

To obtain distance travelled after 10 seconds:-

$S=\int\limits^{10}_0 {6t-0.3t^2} \, dt=|3t^2-0.1t^3| \ *lims(10,0)\\ S=200m$

Therefore 200m is for 10seconds, and next 200m at 30m/s

Total time= $10+\frac{200}{30}=16.67s$

4 0

4 years ago

Carbon dioxide is released when limestone is heated during the production of

Archy [21]

Answer:

Calcium

Explanation:

Because limestone is mainly calcium carbonate, CaCO3, which when heated breaks down to form calcium oxide and carbon dioxide.

6 0

4 years ago

A 1500 kg car skids to a halt on a wet road where μk = 0.47. You may want to review (Pages 141 - 145) . Part A How fast was the

shusha [124]

The car travels at a speed of 25m/s.

<u>Explanation:</u>

Given-

Mass, m = 1500kg

Coefficient of friction, μk = 0.47

Distance, x = 68m

Speed, s = ?

We know,

$Force, F = ma$

and

F = μ X m X g

Therefore,

μ * m * g = m * a

μ * g = a

Let, g = 9.8m/s²

So,

$a = 0.47 * 9.8 m/s^2$

$a = 4.606m/s^2$

We know,

$v^2 - u^2 = 2as$

where, v is the final velocity

u is the initial velocity

a is the acceleration

s is the distance

If the car comes to rest, the final velocity, v becomes 0.

So,

$u^2 = 2 * 4.606 * 68\\\\u^2 = 626.416m/s\\\\u = 25m/s$

The car travels at a speed of 25m/s.

6 0

3 years ago

When are the displacement and acceleration equal to zero for the motion of a mass on a spring?

aliina [53]

Answer:

Option B is the right answer.

5 0

4 years ago