Background: Look at the wheelbarrow in the Figure below . It is used to carry heavy objects. It consists of two simple machines: a lever and a wheel and axle. Effort is applied to the lever by picking up the handles of the wheelbarrow. The lever, in turn, applies upward force to the load. The force is increased by the lever, making the load easier to lift. Effort is applied to the wheel of the wheelbarrow by pushing it over the ground. The rolling wheel turns the axle and increases the force, making it easier to push the load.

Situation: Mike was struggling to carry boxes into his new apartment. Just when he was thinking there had to be an easier way to do this a neighbor offered him a dolly to use. Mike but several boxes on the dolly and pushed down like a lever. The boxes lift up and he was able to push the dolly on it's wheels into his apartment.

Question: What machine did Mike use to lift the boxes?

Situation: Mike was struggling to carry boxes into his new apartment. Just when he was thinking there had to be an easier way to do this a neighbor offered him a dolly to use. Mike but several boxes on the dolly and pushed down like a lever. The boxes lift up and he was able to push the dolly on it's wheels into his apartment.

Question: What machine did Mike use to push the boxes?

Situation: Mike was struggling to carry boxes into his new apartment. Just when he was thinking there had to be an easier way to do this a neighbor offered him a dolly to use. Mike but several boxes on the dolly and pushed down like a lever. The boxes lift up and he was able to push the dolly on it's wheels into his apartment.

Question: Did the dolly make more or less work?

Situation: Mike was struggling to carry boxes into his new apartment. Just when he was thinking there had to be an easier way to do this a neighbor offered him a dolly to use. Mike but several boxes on the dolly and pushed down like a lever. The boxes lift up and he was able to push the dolly on it's wheels into his apartment.

Question: Did the dolly increase or decrease the force on the boxes?

Situation: Mike was struggling to carry boxes into his new apartment. Just when he was thinking there had to be an easier way to do this a neighbor offered him a dolly to use. Mike but several boxes on the dolly and pushed down like a lever. The boxes lift up and he was able to push the dolly on it's wheels into his apartment.

Question: Did the lever increase or decrease the force on the boxes?

Situation: Mike was struggling to carry boxes into his new apartment. Just when he was thinking there had to be an easier way to do this a neighbor offered him a dolly to use. Mike but several boxes on the dolly and pushed down like a lever. The boxes lift up and he was able to push the dolly on it's wheels into his apartment.

Question: Did the wheels increase or decrease the force on the boxes?

Situation: Mike was struggling to carry boxes into his new apartment. Just when he was thinking there had to be an easier way to do this a neighbor offered him a dolly to use. Mike but several boxes on the dolly and pushed down like a lever. The boxes lift up and he was able to push the dolly on it's wheels into his apartment.

Question: Did the dolly increase or decrease Mike's work?