Question 28

If your actual mechanical advantage is 10 J and the theoretical is 40 J, what is your percent efficiency? Hint: % Efficiency = (Actual MA/Ideal MA) * 100

a
0.25%
b
4%
c
400%
d
25%
Question 29
A lever has a mechanical advantage of 4. If you apply a force to the machine with a mass of 4 kg, at an acceleration of 2 m/s/s, what is the output force created by the lever? Hint: Use the equation Fo=MA*Fi.

a
32 N
b
32 J
c
0.5 J
d
0.5 N
Question 30
If an object is in free fall in the absence of air resistance, what is the only force acting on the object?

a
gravity
b
mass
c
acceleration
d
terminal velocity

1 answer

Here are the answers to your questions:

Question 28:
To calculate the percent efficiency, we use the formula:
\[ \text{Percent Efficiency} = \left( \frac{\text{Actual MA}}{\text{Theoretical MA}} \right) \times 100 \]
Substituting in the values:
\[ \text{Percent Efficiency} = \left( \frac{10}{40} \right) \times 100 = 25% \]
Answer: d) 25%

Question 29:
To find the output force (Fo), we use the equation:
\[ Fo = MA \times Fi \]
First, we need to find the input force (Fi). The input force can be calculated using the mass and acceleration:
\[ Fi = \text{mass} \times \text{acceleration} = 4, \text{kg} \times 2, \text{m/s}^2 = 8, \text{N} \]
Now, substituting the values into the output force equation:
\[ Fo = 4 \times 8 = 32, \text{N} \]
Answer: a) 32 N

Question 30:
If an object is in free fall in the absence of air resistance, the only force acting on the object is:
Answer: a) gravity