The "***" is my answer
1.A person pushes a box. He applies a force of 400 newtons, and he pushes the box for a distance of 4 meters. After he stops pushing, the box slides forward another meter. How much work was done by the person?
A. 400 joules
B. 1600 joules***
C. 2000 joules
D. 100 joules
2.In this pulley system, the pulleys will _____ the mechanical force required to lift the block and will change the _____.
A. decrease; direction of the force
B. increase; direction of force***
C. increase; weight of the block
D. decrease; weight of the block
3.Which list correctly orders effort (E), fulcrum (F), and load (L) for each lever class?
A. class 1 = F, L, E (or E, L, F)
class 2 = F, E, L(or L, E, F
class 3 = L, F, E (or E, F, L
B. class 1 = L, F, E (or E, F, L ***
class 2 = F, L, E (or E, L, F
class 3 = L, E, L (or L, E, L
C. class 1 = F, E, L (or L, E, F
class 2 = L, F, E (or E, F, L
class 3 = F, L, E (or E, L, F
D. class 1 = F, E, L (or L, E, F
class 2 = F, L, E (or E, L, F
class 3 = L, F, E (or E, F, L
4. How do simple machines make work easier?
a. they decrease the distance needed between a person and an object, allowing the person to apply more force and do more work
b. they reduce the amount of force needed to move an
object to do the same amount of work ***
c. they magnify the force being applied, thereby decreasing the work they can do with no extra energy exerted by the person using the machine
d. they increase the distance over which a force is needed, doing more work with less force
5. A person using a lever applies 98 Newtons to lift a 20-kilogram box. They apply the force over a distance of 4 meters to lift the box a distance of 2 meters. How much work is done?
A. 392 joules
B. 40 joules
C. 80 joules
D. 196 joules***
6. A person is lifting a heavy box using a lever. What is the purpose of the lever in this situation?
A. to reduce the energy needed to lift the box while keeping the direction of the force the same
B. to reduce the energy needed to life the box and change the direction of the force ***
c. to reduce the force needed to life the box while keeping the direction of the force the same
d. to reduce the force needed to lift the box and change the direction of the force
7. Use the image of a person lifting a boulder with a lever to answer the question.
Where is the fulcrum in this situation?
A. it is the point where the boulder touches the ground. ***
B. it is the point where the person's hand pushes down of the bar
C. it is the point where the bar touches the boulder.
D. it is the point where the bar touches the smaller rock
8. In which situation did the car achieve the greatest efficiency? (Assume the cars all have the same mass.)
A. a car that traveled 80 kilometers on 5.0 liters of gas ***
B. a car that traveled 70 kilometers on 5.0 liters of gas
c. a car that traveled 90 kilometers on 6.0 liters of gas
d. a car that traveled 50 kilometers on 4.0 liters of gas
9. Use the table
machine output work input work
a 750 1500
b 1000 4000
c 450 600
d 3000 5000
Which machine has the highest efficiency?
A. machine b ***
B. machine c
C. machine a
D. machine d
1. 1,600 joules
2. decrease; direction of the force
3. class 1 = L, F, E (or E, F, L)
class 2 = F, L, E (or E, L, F)
class 3 = F, E, L (or L, E, F)
4. They reduce the amount of force needed to move an object to do the same amount of work.
5. 392 Joules
6. to reduce the force needed to lift the box and change the direction of the force
7. It is the point where the bar touches the smaller rock.
8. a car that traveled 80 kilometers on 5.0 liters of gas
9. machine C
10. It changes the direction of the lifting force to work with gravity.
11.Use a stiffer lever to reduce energy lost bending the lever.
12. 60%
These answers are 100% i pinky promise!