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Nikitich [7]
3 years ago
12

A car travels first 30 km at a uniform speed of 20 km

Physics
1 answer:
masha68 [24]3 years ago
6 0

Answer:

20 = 30 / t1

t1 = 3/2

40 = 30 / t2

t2 = 3/4

average speed = total distance / total time taken

= 30 + 30 / 3/2 + 3/4

= 60 /9/4

= 60 × 4/9

= 26.667

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A 2.0 kg, 20-cm-diameter turntable rotates at 100 rpm ons tionless bearings. Two 500 g blocks fall from above, hit the tum ble s
Verdich [7]

There are mistakes in the question.The correct question is here

A 2.0 kg, 20-cm-diameter turntable rotates at 100 rpm on frictionless bearings. Two 500 g blocks fall from above, hit the turntable simultaneously at opposite ends of a diameter, and stick. What is the turntable’s angular velocity, in rpm, just after this event?

Answer:

w=50 rpm

Explanation:

Given data

The mass turntable M=2kg

Diameter of the turntable d=20 cm=0.2 m

Angular velocity ω=100 rpm= 100×(2π/60) =10.47 rad/s

Two blocks Mass m=500 g=0.5 kg

To find

Turntable angular velocity

Solution

We can find the angular velocity of the turntable as follow

Lets consider turntable to be disk shape and the blocks to be small as compared to turntable

I_{turntable}w=I_{block1}w^{i}+I_{turntable}w^{i}+I_{block2}w^{i}

where I is moment of inertia

w^{i}=\frac{I_{turntable}w}{I_{block1}w^{i}+I_{block2}w^{i}+I_{turntable}w^{i}}\\   So\\I_{turntable}=M\frac{r^{2} }{2}\\I_{turntable}=2*(\frac{(0.2/2)}{2} )\\ I_{turntable}=0.01 \\And\\I_{block1}=I_{block2}=mr^{2}\\I_{block1}=I_{block2}=(0.5)*(0.2/2)^{2} \\ I_{block1}=I_{block2}==0.005\\so\\w^{i}=\frac{I_{turntable}w}{I_{block1}w^{i}+I_{block2}w^{i}+I_{turntable}w^{i}}\\w^{i}=\frac{0.01*(10.47)}{0.005+0.005+0.01} \\w^{i}=5.235 rad/s\\w^{i}=5.235*(60/2\pi )\\w^{i}=50 rpm

7 0
3 years ago
A automotive test driver travels due north in a prototype hybrid vehicle at 30 mi/h
Nikolay [14]

Answer:

Option A. 40 mi/h

Explanation:

To obtain the average speed of the vehicle, we'll begin by calculating the distance travelled by the vehicle in each case. This is illustrated below:

Case 1:

Speed = 30 mi/h

Time = 2 h

Distance =...?

Speed = Distance /Time

30 = Distance /2

Cross multiply

Distance = 30 × 2

Distance = 60 mi

Case 2:

Speed = 60 mi/h

Time = 1 h

Distance =...?

Speed = Distance /Time

60 = Distance /1

Cross multiply

Distance = 60 × 1

Distance = 60 mi

Finally, we shall determine the average speed of the vehicle as follow:

Total distance travelled = 60 + 60

Total distance travelled = 120 mi

Total time = 2 + 1

Total time = 3 h

Average speed =..?

Average speed = Total Distance travelled /Total time

Average speed = 120/3

Average speed = 40 mi/h

Therefore, the average speed of the vehicle is 40 mi/h

3 0
4 years ago
A lever has a mechanical advantage of 5.4. If you apply a force of 500 N to the lever, how much force does the lever apply to th
Yanka [14]

Force applied by the lever to the object=2700 N

Explanation:

Mechanical advantage= \frac{LOAD}{EFFORT}

mechanical advantage= 5.4

effort force= 500 N

we need the load force

5.4= load/500

load=2700 N

Thus the force applied by the lever to the object=2700 N

6 0
3 years ago
A force has both a _____ and a _____. A. mass; direction B. magnitude; mass C. magnitude; direction
kipiarov [429]
C. magnitude & direction
3 0
3 years ago
One mole of a gas is placed in a closed system with a 20 L vessel initially at T = 300 K. The vessel is then isothermally expand
Elden [556K]

Answer:

Given that

P = RT/V + a/V²

We know that

H= U + PV

For T= Constant  (ΔU=0)

ΔH= ΔU +Δ( PV)

ΔH= Δ( PV)

P = RT/V + a/V²

P V= RT + a/V

dH/dV = d(RT + a/V)/dV

dH/dV = - a/V²

So the expression of dH/dV

\dfrac{dH}{dV}=\dfrac{-a}{V^2}

b)

In isothermal process

\Delta H=nRT\ln{\dfrac{V_2}{V_1}}      (ΔU=0)

Now by putting the all values

\Delta H=nRT\ln{\dfrac{V_2}{V_1}}

\Delta H=1\times 0.08206\times 300\ln{\dfrac{40}{20}}

ΔH = 17.06 L.atm

8 0
3 years ago
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