Question

Marvin can exert a force of 180 lbs. How heavy a rock can he lift is he uses a crowbar that is 5 ft. long and if he places the fulcrum so that it is 6 in. from the rock?

Answer 1

Marvin can lift a rock that weighs up to 18 lbs using a crowbar.

Step-by-step explanation:

To determine the weight of the rock that Marvin can lift using a crowbar, we can use the principle of lever mechanics. We know that the force Marvin can exert is 180 lbs.

The force Marvin applies on the crowbar will be multiplied by the length of the crowbar on one side of the fulcrum, and this will be equal to the weight of the rock multiplied by the length of the crowbar on the other side of the fulcrum.

Let's use the formula:

Force1 × Length1 = Force2 × Length2

where Force1 is the force applied by Marvin (180 lbs), Length1 is the length of the crowbar on one side of the fulcrum (6 in. or 0.5 ft), Force2 is the weight of the rock (in lbs) that Marvin can lift, and Length2 is the length of the crowbar on the other side of the fulcrum (5 ft).

Rearranging the formula to solve for Force2, we have:

Force2 = (Force1 × Length1) / Length2

Plugging in the values, we get: Force2 = (180 lbs × 0.5 ft) / 5 ft = 18 lbs.

Therefore, Marvin can lift a rock that weighs up to 18 lbs using the crowbar.

Answer 2

This can be set up as a ratio of the mechanical advantage of the crowbar ( length of crowbar divided by the fulcrum point) and the amount of effort applied:

Weight of the rock = (Effort x length of crowbar in inches) / fulcrum.

Weight of rock = (180 lbs x 60) / 6

Weight of rock= 10800 / 6

Weight of rock = 1,800 pounds.