A girl pushes her little brother on his sled w/ a force of 35N for 840s. How much work does she do if the force of friction I'd 27N?
I subtracted the force of friction from the applied force to get my net force of 8N but I don't know where to go from there...
Thank you :)
To calculate the work done by the girl, you need to find the distance covered by the sled.
First, let's determine the net force acting on the sled. As you correctly mentioned, the net force is the difference between the applied force (35N) and the force of friction (27N). Therefore, the net force is 35N - 27N = 8N.
Next, recall that work is defined as the product of force and displacement. So, you need to find the displacement of the sled.
To calculate the displacement, you can use the formula:
displacement = (force * time) / mass
Since the sled is not given a mass, we don't have enough information to directly calculate displacement. However, we can use another formula to calculate work.
Another formula for work is:
work = force * distance * cosine(theta)
In this case, the girl is pushing the sled in a straight line, so the angle between the force and the direction of motion (theta) is 0 degrees. Therefore, cosine(theta) is 1.
With that information, we can calculate the work done by the girl using the formula:
work = force * distance * cosine(theta)
Plugging in the values, we get:
work = 8N * distance * 1
Now, we need to find the distance. The relationship between distance, time, and velocity can be represented by the formula:
distance = velocity * time
Since the sled is being pushed by a constant force, it will accelerate until the force of friction equals the applied force, resulting in a constant velocity. Therefore, the distance can be calculated as the product of the velocity and the time:
distance = velocity * time
Now, we have the information we need to calculate the work done by the girl:
work = 8N * distance * 1
work = 8N * (velocity * time) * 1
work = 8N * (velocity * 840s) * 1
Unfortunately, we don't have enough information to directly calculate the velocity. However, if we assume that the sled starts from rest, then the final velocity can be approximated as the average velocity over the time interval.
So, we can estimate the average velocity as:
velocity = (0m/s + final velocity) / 2
Since the sled starts from rest, the initial velocity is 0m/s. Therefore, the average velocity becomes:
velocity = (0m/s + final velocity) / 2
velocity = final velocity / 2
Now, we can rewrite the work equation:
work = 8N * (velocity * 840s) * 1
work = 8N * [(final velocity / 2) * 840s] * 1
At this point, we cannot proceed without knowing the final velocity of the sled.
If additional information is provided, such as the final velocity or the mass of the sled, we can calculate the total work done by the girl.