11. A 3.8 kg object is lifted 12 meters. Approximately how much work is performed during the lifting?

At t = 0 a grinding wheel has an angular velocity of 24.0 rad/s. It has a constant angular acceleration of 30.0rad/s2 until a ci

kozerog [31]

Answer:

θ=108rad

t =10.29seconds

α=-8.17rad/s²

Explanation:

Given that

At t=0, Wo=24rad/sec

Constant angular acceleration =30rad/s²

At t=2, θ=432rad as it try to stop because the circuit break

Angular motion

W=Wo+αt

θ=Wot+1/2αt²

W²=Wo²+2αθ

We need to find θ between 0sec to 2sec when the wheel stop

a. θ=Wot+1/2αt²

θ=24×2+1/2×30×2²

θ=48+60

θ=108rad.

b. W=Wo+αt

W=24+30×2

W=84rad/s

This is the final angular velocity which is the initial angular velocity when the wheel starts to decelerate.

Wo=84rad/sec

W=0rad/s, because the wheel stop at θ=432rad

Using W²=Wo²+2αθ

0²=84²+2×α×432

-84²=864α

α=-8.17rad/s²

It is negative because it is decelerating

Now, time taken for the wheel to stop

W=Wo+αt

0=84-8.17t

-84=-8.17t

Then t =10.29seconds.

a. θ=108rad

b. t =10.29seconds

c. α=-8.17rad/s²

3 0

3 years ago

Although planets orbit the Sun in ellipses, all the planetary orbits are fairly close to circular and not very eccentric.

Nutka1998 [239]

Answer:

False

Explanation:

The Sun rotates in this same, right-hand-rule direction. All planetary orbits lie in nearly the same plane. All planetary orbits are nearly circular (eccentricity near zero).

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8 0

2 years ago

Azaria's pet lizard runs a distance of 45 meters in 24 seconds. What is the speed of the lizard?

san4es73 [151]

Question:

Azaria's pet lizard runs a distance of 45 meters in 24 seconds. What is the speed of the lizard?

_________________________________________________

Solution:

We are given,

Distance = d = 45 m
Time = t = 24 s

Speed is given by:

Speed = s = d/t

Putting the given values,

s = (45 m)/(24 s)

=> s = 1.875 m/s

_________________________________________________

3 0

2 years ago

A straight wire in a magnetic field experiences a force of 0.023 N when the current in the wire is 2.5 A. The current in the wir

Tatiana [17]

Answer:

The new current in the wire is 6.3 A.

Explanation:

Given that,

Force in a straight wire, F = 0.023 N

Current in the wire, I = 2.5 A

If new force is, F' = 0.058 N, we need to find the new current.

We know that, magnetic force is given by :

$F=ilB\sin\theta$

It is clear that force is directly proportional to electric current. So, we can say:

$\dfrac{F}{F'}=\dfrac{I}{I'}$

I' is new current

$I'=\dfrac{IF'}{F}\\\\I'=\dfrac{2.5\times 0.058}{0.023}\\\\I'=6.3\ A$

So, the new current in the wire is 6.3 A. Hence, this is the required solution.

8 0

3 years ago

In 2 minutes, a ski lift raises four skiers at a constant speed to a height of 123 m. The average mass of each skier is 71 kg. W

serious [3.7K]

Answer:

The average power provided by the tension in the cable pulling the lift is = 714 W

Explanation:

Given data

Mass = 71 kg

Change in height = 123 m

When the lift moves in upward direction then in that case kinetic energy is constant & only potential energy changes.

Change in potential energy Δ PE = m g ( $h_f - h _ i$ )

Δ PE = 71 × 9.81 × 123

Δ PE = 85670.73 J

Time = 2 min = 120 sec

So average power is given by

$P_{avg} = \frac{Change \ in \ potential \ energy}{Time}$

$P_{avg} = \frac{85670.73}{120}$

$P_{avg} = 714 \ W$

Therefore the average power provided by the tension in the cable pulling the lift is = 714 W

7 0

3 years ago