a 45kg box of books is lifted o a bookself 1.75 m above the floor. how much work was done to lift the books?
1 answer:
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Answer:
Explanation:
<u>Accelerated Motion </u>
When a body changes its speed at a constant rate, i.e. same changes take same times, then it has a constant acceleration. The acceleration can be positive or negative. In the first case, the speed increases, and in the second time, the speed lowers until it eventually stops. The equation for the speed vf at any time t is given by
where a is the acceleration, and vo is the initial speed .
The train has two different types of motion. It first starts from rest and has a constant acceleration of for 182 seconds. Then it brakes with a constant acceleration of
until it comes to a stop. We need to find the total distance traveled.
The equation for the distance is
Our data is
Let's compute the first distance X1
Now, we find the speed at the end of the first period of time
That is the speed the train is at the moment it starts to brake. We need to compute the time needed to stop the train, that is, to make vf=0
Computing the second distance
The total distance is