# i need help please and fast.

How do simple machines make work easier?(1 point)

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 increase the distance over which a force is needed, doing more work with less force.
C.They reduce the amount of force needed to move an object to do the same amount of work.
D.They magnify the force being applied, thereby decreasing the work they can do with no extra energy exerted by the person using the machine.

In which situation did the car achieve the greatest efficiency? (Assume the cars all have the same mass.)(1 point)

A.a car that traveled 70 kilometers on 5.0 liters of gas
B.a car that traveled 90 kilometers on 6.0 liters of gas
C.a car that traveled 80 kilometers on 5.0 liters of gas
D.a car that traveled 50 kilometers on 4.0 liters of gas

machine 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?
machine A
machine B
machine C
machine D

What is the efficiency of a ramp if 2,000 joules of energy results in 1,200 joules of work?(1 point)

24%
32%
60%
80%

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## To answer the first question, "How do simple machines make work easier?", you need to understand the basic principles of simple machines. Simple machines are devices that can change the magnitude or direction of a force, making it easier to accomplish work. The correct answer is C. They reduce the amount of force needed to move an object to do the same amount of work. By using simple machines, the force required to move an object can be decreased, allowing for easier work.

To determine which situation achieved the greatest efficiency among the cars, you need to calculate the efficiency of each car. Efficiency is the ratio of output work to input work, multiplied by 100% to express it as a percentage. The formula for efficiency is (Output work/Input work) x 100%.

Let's calculate the efficiency for each situation:

Situation A: Efficiency = (70 km / 5.0 L) x 100% = 14 km/L
Situation B: Efficiency = (90 km / 6.0 L) x 100% = 15 km/L
Situation C: Efficiency = (80 km / 5.0 L) x 100% = 16 km/L
Situation D: Efficiency = (50 km / 4.0 L) x 100% = 12.5 km/L

From the calculations, we can see that situation C, where the car traveled 80 kilometers on 5.0 liters of gas, achieved the highest efficiency with 16 km/L.

To determine which machine has the highest efficiency in the given scenario, we again need to calculate the efficiency for each machine using the formula mentioned earlier.

Machine A: Efficiency = (750 J / 1,500 J) x 100% = 50%
Machine B: Efficiency = (1,000 J / 4,000 J) x 100% = 25%
Machine C: Efficiency = (450 J / 600 J) x 100% = 75%
Machine D: Efficiency = (3,000 J / 5,000 J) x 100% = 60%

From the calculations, we can conclude that machine C has the highest efficiency, with an efficiency of 75%.

To find the efficiency of a ramp, you need to use the same formula of efficiency: (Output work / Input work) x 100%. In this case, the output work is 1,200 joules and the input work is 2,000 joules. Let's calculate the efficiency:

Efficiency = (1,200 J / 2,000 J) x 100% = 60%

Therefore, the efficiency of the ramp is 60%.

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