College

Select the correct answer.

The amount of force, [tex]F[/tex], needed to lift an object using a lever varies inversely as the length, [tex]L[/tex], of the lever. When a 24-inch lever is used, a force of 240 pounds is needed. How much force is needed if a 36-inch lever is used?

A. 120 pounds
B. 160 pounds
C. 252 pounds
D. 360 pounds

Answer :

To solve this problem, we need to understand the concept of inverse variation. In this context, the amount of force [tex]F[/tex] needed to lift an object with a lever varies inversely with the length [tex]L[/tex] of the lever. The relationship can be expressed by the formula:

[tex]F \times L = k[/tex]

where [tex]k[/tex] is a constant.

First, we are given that when a 24-inch lever is used, a force of 240 pounds is needed. We can use this information to find the constant [tex]k[/tex]:

[tex]240 \times 24 = k[/tex]
[tex]k = 5760[/tex]

Now, we know that for any other length of the lever, the product of the force and the length must equal 5760.

We need to find the force [tex]F[/tex] required for a 36-inch lever:

[tex]F \times 36 = 5760[/tex]

To find [tex]F[/tex], divide both sides by 36:

[tex]F = \frac{5760}{36}[/tex]
[tex]F = 160[/tex]

Therefore, a force of 160 pounds is needed if a 36-inch lever is used. The correct answer is:

B. 160 pounds

This solution shows how the inverse relationship between force and lever length can be used to calculate the force required for different lever lengths.

Answer:

B. 160 pounds

Explanation:

We can find the force with the formula:

[tex]\red{\boxed{\bf F=\dfrac{k}{L} }}[/tex]

  • F = force
  • k = constant of variation
  • L = length

[tex]240=\dfrac{k}{24}[/tex]

[tex]k=240\times24[/tex]

[tex]\implies k=5760[/tex]

We find the force when L= 36 inches:

[tex]F=\dfrac{5760}{36}[/tex]

[tex]\implies\bf F= 160\:pounds[/tex]