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Alinara [238K]
3 years ago
10

A child carries a 3N book at a constant velocity of 4 meters across a horizontal floor. What is the net work done?

Physics
1 answer:
s2008m [1.1K]3 years ago
6 0
This problem is getting you used to the definition of 'work' = (force) x (distance).

It's hard to really imagine, but technically, when an object moves horizontally,
no work is done, because there's no lifting against the force of gravity.

Another way to look at it:  The potential energy of the object never changes,
because its height never changes, so no energy ever goes into it ot gets
taken out of it.

Also, if the object moves at a constant speed, then it never accelerated,
and that means that no force ever acted on it.

So technically, when an object moves horizontally at a constant speed,
the work done on it is zero.
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Answer: independent variable: Size of the feather.

Explanation:

In an experiment, the manipulated/independent variable is, as the name implies, the variable that the scientist can control.

In this case, the scientist has only one variable that he can control at will, and this is the size of the feather (he can choose which feather he uses for the experiment)

So the manipulated variable will be the size of the feather.

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A hammer of mass M is moving at speed v0 when it strikes a nail of negligible mass that is stuck in a wooden block. The hammer i
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3 years ago
A 35.4 kg girl is riding on the back of a 15.23 kg cart. the cart and the kid are both moving eastward at 4.25 m/s when she step
Grace [21]

Answer:

The final  velocity of the cart is  v_c = 7.02 \  m/s

Explanation:

From the question we are told that

    The mass of the girl is  m_g  = 35.4 \ kg

     The mass of the cart is  m_c  = 15.23 \ kg

      The speed of the cart and  kid(girl) is  v = 4.25 \ m/s

     The final velocity of  the girl is v_g  = 3.06 \  m/s

Let assume that velocity eastward is  positive and velocity westward is negative (Note that if we assume vise versa it wouldn't affect the answer )

   The total momentum of the system before she steps off the back of the cart

is mathematically evaluated as

        p__{T1}} = (m_g + m_c) * v

substituting values

        p__{T1}} = (35.4 + 15.23) * 4.25

        p__{T1}} =215.17 \  kg m /s

The total momentum after she steps off the back of the cart is mathematically evaluated as

        p__{T2}} = (m_g * v_g ) +(  m_c * v_c )

Where  v_c  is the final velocity of the cart

substituting values    

      p__{T2}} = (35.4 * 3.06 ) +(  15.23 * v_c )

       p__{T2}} = 108. 324 + 15.23  v_c

Now according to the law of conservation of momentum

       p__{T1}} =p__{T2}}

So  

       215.17 \  kg m /s =  108. 324 + 15.23  v_c

=>      v_c = 7.02 \  m/s

Since the value is positive it implies that the cart moved eastward

7 0
3 years ago
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Explanation:

1)5.8m/s

2)5.15m/s^2

3)12.69m/s

4)

8 0
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