A 17.5-kg block is dragged over a rough, horizontal surface by a 75-N force acting at 21° above the horizontal. The block is dis
placed 5.7 m, and the coefficient of kinetic friction is 0.150.
Requried:
a. Find the work done on the block by the 75-N force.
b. Find the work done on the block by the normal force.
c. Find the work done on the block by the gravitational force.
d. What is the increase in internal energy of the block-surface system due to friction?
e. Find the total change in the block's kinetic energy.
Requried:
a. Find the work done on the block by the 75-N force.
b. Find the work done on the block by the normal force.
c. Find the work done on the block by the gravitational force.
d. What is the increase in internal energy of the block-surface system due to friction?
e. Find the total change in the block's kinetic energy.
1 answer:
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Answers:
a) 9.035 s
b) -88.543 m/s
Explanation:
The described situation is related to vertical motion (especifically free fall) and the equations that will be useful are:
(1)
(2)
Where:
is the final height of the steel ball
is the initial height of the steel ball
is the initial velocity of the steel ball (it was dropped)
is the final velocity of the steel ball
is the time it takes to the steel ball to reach the ground
is the acceleration due to gravity
<u>Knowing this, let's begin with the answers:</u>
<h2>a) Time it takes the steel ball to reach the ground</h2>We will use equation (1) with the conditions listed above:
(3)
Isolating :
(4)
(5)
(6)
We will use equation (2) with the conditions explained above and the calculaated time:
(7)
(8)
(9) The negative sign indicates the direction of the velocity is downwards