The "***" is my answer
1. 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
2. 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
3. Use the table
Which machine has the highest efficiency?
A. machine b ***
B. machine c
C. machine a
D. machine d
6 answers
a 750 1500
b 1000 4000
c 450 600
d 3000 5000
wE both need our answers checked on this quiz
2. Agree
3. Agree
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?
Responses
1,600 joules*****
2,000 joules
100 joules
400 joules
2. In this pulley system, the pulleys will _____ the mechanical force required to lift the block and will change the _____.
Responses
decrease; direction of the force*****
decrease; weight of the block
increase; direction of the force
increase; weight of the block
3. Which list correctly orders effort (E), fulcrum (F), and load (L) for each lever class?
Responses
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)
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)
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)
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?
Responses
They increase the distance over which a force is needed, doing more work with less force.
They reduce the amount of force needed to move an object to do the same amount of work.******
They decrease the distance needed between a person and an object, allowing the person to apply more force and do more work.
They magnify the force being applied, thereby decreasing the work they can do with no extra energy exerted by the person using the machine.
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?
Responses
392 Joules*****
80 Joules
40 Joules
196 Joules
6. A person is lifting a heavy box using a lever. What is the purpose of the lever in this situation?
Responses
to reduce the force needed to lift the box and change the direction of the force*****
to reduce the force needed to lift the box while keeping the direction of the force the same
to reduce the energy needed to lift the box while keeping the direction of the force the same
to reduce the energy needed to lift the box and change the direction of the force
7. Where is the fulcrum in this situation?
Responses
It is the point where the bar touches the boulder.
It is the point where the boulder touches the ground.
It is the point where the bar touches the smaller rock.*****
It is the point where the person’s hands push down on the bar.
8. In which situation did the car achieve the greatest efficiency? (Assume the cars all have the same mass.)
Responses
a car that traveled 90 kilometers on 6.0 liters of gas
a car that traveled 70 kilometers on 5.0 liters of gas
a car that traveled 50 kilometers on 4.0 liters of gas
a car that traveled 80 kilometers on 5.0 liters of gas****
9.
Output Work (J)Input Work (J)
A 750 1,500
B 1,000 4,000
C 450 600
D 3,000 5,000
Which machine has the highest efficiency?
Responses
machine D
machine A
machine C****
machine B
10. How does a pulley make work easier when it is used to lift an object?
Responses
It increases the amount of work produced to lift the object.
It changes the direction of the lifting force to work with gravity.*****
It decreases the distance over which the force must be applied to lift the object.
It reduces the weight of the object being lifted.
11. A certain lever system is only 30% efficient. What could make it more efficient?
Responses
Use it with a lighter load to make it easier.
Make a longer lever that will require less force.
Use a stiffer lever to reduce energy lost bending the lever.******
Have more than one person help to lift the lever.
12.What is the efficiency of a ramp if 2,000 joules of energy results in 1,200 joules of work?
Responses
60%****
24%
80%
32%
I rlly hope this helps... :)