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Alex17521 [72]
3 years ago
12

An initially stationary 2.7 kg object accelerates horizontally and uniformly to a speed of 13 m/s in 4.0 s. (a) In that 4.0 s in

terval, how much work is done on the object by the force accelerating it? What is the instantaneous power due to that force (b) at the end of the interval and (c) at the end of the first half of the interval?
Physics
1 answer:
Ronch [10]3 years ago
8 0

Explanation:

A.

Given:

V = 13 m/s

t = 4 s

Constant acceleration, a= (V-Vi)/t

= 13/4

= 3.25 m/s^2

F = mass * acceleration

= 2.7 * 3.25

= 8.775 N.

Using equations of motion,

distance,S = (13 * 4) - (1/2)(3.25)(4^2)

= 26 m

Workdone, W = force * distance

= 8.775 * 26

= 228.15 J

B.

Instantaneous power, P = Force *Velocity

= 8.775 * 13

= 114. 075 W

C.

t = 2 s,

Constant acceleration, a= (V-Vi)/t

= 13/2

= 6.5 m/s^2

Force = mass * acceleration

= 2.7 * 6.5

= 17.55 N

Instantaneous power, P = Force *Velocity

= 17.55 * 13

= 228.15 W.

= 114. 075 W.

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First solve the potential energy of the biker. using the fomula:
PE = mgh
where m  is the mass of the object
g is the acceleration due to gravity ( 9.81 m/s2)
h is the height

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PE = 1054771.2 J
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P = 1054771.2 J / ( 120 min ) ( 60 s / 1 min)
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8 0
3 years ago
A thin rod rotates at a constant angular speed. Consider the tangential speed of each point on the rod for the case when the axi
ASHA 777 [7]

Answer:

    v = R w    

With this expression we see that for each point at different radius the tangential velocity is different

Explanation:

They indicate that the angular velocity is constant, that is

            w = dθ / dt

Where θ is the radius swept angle and t the time taken.

The tangential velocity is linear or

           v = dx / dt

Where x is the distance traveled in time (t)

 

In the definition of radians

          θ = s / R

Where s is the arc traveled and R the radius vector from the pivot point, if the angle is small the arc (s) and the length (x) are almost equal

         θ = x / R

We substitute in the speed equation

         v = d (θ R) / dt

The radius is a constant for each point

         v = R dθ / dt

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With this expression we see that for each point at different radius the tangential velocity is different

6 0
2 years ago
Figure 1.18 (Chapter 1) shows the Hoover Dam Bridge over
stiks02 [169]

Answer: 7.436 s

Explanation:

This situation is related to vertical motion, specifically free fall and can be modelled by the following equation:

y=y_{o}+V_{o} t+\frac{gt^{2}}{2}  

Where:

y= 0m is the final height of the object (when it makes splash)

y_{o}=271 m  is the initial height of the object

V_{o}=0 m/s  is the initial velocity of the object (it was dropped)

g=-9.8m/s^{2}  is the acceleration due gravity (directed downwards)

t is the time since the objecct is dropped until it makes splash

0=y_{o}+0+\frac{gt^{2}}{2}  

Clearing t:

t=\sqrt{\frac{-2y_{o}}{g}}  

t=\sqrt{\frac{-2(271 m)}{-9.8m/s^{2}}}  

Finally:

t=7.436 s  

6 0
3 years ago
A rock is dropped into the Grand Canyon. It takes 18 seconds to hit the bottom. Calculate how deep the canyon is.
bonufazy [111]
The distance it falls is given by
x = (1/2)at^2
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6 0
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How fast can a 4000 kg truck travel around a 70 m radius turn without skidding if its tires share a 0.6 friction coefficient wit
aleksley [76]

Answer:

Velocity of truck will be 20.287 m /sec

Explanation:

We have given mass of the truck m = 4000 kg

Radius of the turn r = 70 m

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And frictional force is equal to F_{frictional}=\mu mg

For body to be move these two forces must be equal

So \frac{mv^2}{r}=\mu mg

v=\sqrt{\mu rg}=\sqrt{0.6\times 70\times 9.8}=20.287m/sec

7 0
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