Question

B

A 20.0 kg object is at rest, and then speeds up to 16.0 m/s. How much work was done on this system?
320 J
2,560 J
2,880 J
5,120 J
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Answer 1

5,120 J

Step-by-step explanation:

The work done (W) on an object is given by the equation:

�

=

1

2

�

�

2

W=

2

1

​

mv

2

where:

�

m is the mass of the object,

�

v is the final velocity of the object.

Given:

�

=

20.0

 

kg

m=20.0kg,

�

=

16.0

 

m/s

v=16.0m/s,

Substitute these values into the equation:

�

=

1

2

×

20.0

 

kg

×

(

16.0

 

m/s

)

2

W=

2

1

​

×20.0kg×(16.0m/s)

2

�

=

1

2

×

20.0

 

kg

×

256.0

 

m

2

/

s

2

W=

2

1

​

×20.0kg×256.0m

2

/s

2

�

=

5

,

120

 

J

W=5,120J

So, the correct answer is:

5,120 J