I have a few physics questions:
1. How much mechanical work is done by a weightlifter holding a mass of 100 kg, 2.0m above the floor for 3.0 s? Explain ur answer.
2. Calculate the force needed to do 2.0 kJ of work to push a load of bricks 10m?
3. A carpenter applied a force of 60N horizontally to push a plane 40cm along a piece of wood, how much work does he do?
4. A librarian does 8.0J of work to stack five identical books on top of each other. If each book has a thickness of 4.0cm what is the mass of each book?
They never did help you huh
you don't understand i don't get this unit and i'm failling this unit miserabely really need help
ok so here's how i thought i would have to solve these:
1. W=mgh
=100*9.8*2.0
or w=0 because u lift the mass upards and carry it (perpenticular ) hence w=0
2. W=f delta D
W/D=Force
3. W=60N * 40cm (ordo i convert 40 cm to kg)
4. W=mgh
W/h=m (do i convert 4.0 cm to kg?)
It appears you are posting several questions under different names. Sorry.
Show your work. I will be happy to critique your work and thinking.
1. To calculate the mechanical work done by a weightlifter, we can use the formula:
Work = Force * Distance * cos(theta)
In this case, the force is the weight of the mass (100 kg) which can be calculated as:
Force = Mass * Acceleration due to gravity = 100 kg * 9.8 m/s^2
The distance is given as 2.0 m, and theta is the angle between the applied force and the direction of motion, which is 0 degrees in this case since the force is directly upwards.
So, substituting the values into the formula:
Work = (100 kg * 9.8 m/s^2) * 2.0 m * cos(0 degrees)
Since cos(0 degrees) is equal to 1, the work done by the weightlifter is:
Work = (100 kg * 9.8 m/s^2) * 2.0 m
2. To find the force needed to do work, we can use the formula:
Work = Force * Distance
Given that the work done is 2.0 kJ (kilojoules) and the distance is 10 m, we need to convert the work into joules:
2.0 kJ * 1000 J/kJ = 2000 J
Now we can rearrange the formula to solve for force:
Force = Work / Distance
Substituting the values:
Force = 2000 J / 10 m
3. To calculate the work done by the carpenter, we can use the formula:
Work = Force * Distance * cos(theta)
In this case, the force is given as 60 N, the distance is 40 cm, and theta is the angle between the applied force and the direction of motion. Since the force is applied horizontally and the motion is also horizontal, the angle theta is 0 degrees.
So, substituting the values into the formula:
Work = 60 N * 40 cm * cos(0 degrees)
Now, we need to convert the distance from centimeters to meters:
40 cm * 0.01 m/cm = 0.4 m
Substituting the values again:
Work = 60 N * 0.4 m
4. To calculate the mass of each book, we need to use the formula:
Work = Force * Distance
In this case, the force is the weight of the book, which can be calculated as:
Force = Mass * Acceleration due to gravity
The thickness of each book is given as 4.0 cm, which can be converted to meters:
4.0 cm * 0.01 m/cm = 0.04 m
The distance is the height of the stack of books, which is the thickness of each book multiplied by the number of books minus one:
Distance = 0.04 m * (5 - 1)
Now, substituting the values into the formula:
8.0 J = (Mass * 9.8 m/s^2) * (0.04 m * 4)
Simplifying:
8.0 J = Mass * 9.8 m/s^2 * 0.16 m
Dividing both sides by (9.8 m/s^2 * 0.16 m):
Mass = 8.0 J / (9.8 m/s^2 * 0.16 m)