Background: All machines make work easier, but they don’t increase the amount of work that is done. You can never get more work out of a machine than you put into it. In fact, a machine always does less work on an object than the user does on the machine. That’s because a machine must use some of the work put into it to overcome friction. Friction is the force that opposes motion between any surfaces that are touching. All machines involve motion, so they all have friction. How much work is needed to overcome friction in a machine depends on the machine’s efficiency.

Situation: Andrew just moved into his new apartment but realized he made a mistake. He loaded a box too heavy for him to lift. He decides to try to push the mox into his house from the back of his building which has a very rough path and struggles to get the box in the house.

Question: Given the pavement in front of Andrews apartment is much smoother would it be easier or harder to push the box inside?
Answer: easier

Situation: Andrew just moved into his new apartment but realized he made a mistake. He loaded a box too heavy for him to lift. He decides to try to push the mox into his house from the back of his building which has a very rough path and struggles to get the box in the house.

Question: Will the amount of effort needed to push something across a rough surface increase or decrease as compared to a smooth surface?
Answer: increase

Situation: Andrew just moved into his new apartment but realized he made a mistake. He loaded a box too heavy for him to lift. He decides to try to push the mox into his house from the back of his building which has a very rough path and struggles to get the box in the house.

Question: Will reducing friction increase of decrease the effort needed to push an object?
Answer: decrease

Situation: Andrew just moved into his new apartment but realized he made a mistake. He loaded a box too heavy for him to lift. He decides to try to push the mox into his house from the back of his building which has a very rough path and struggles to get the box in the house.

Question: Will decreasing the amount of friction make pushing an object more difficult or less difficult?
Answer: less

Situation: During the summer Anthony found it was way too hot to be comfortable. He went out to his garage to get an old fan. The fan was spins on a metal bearing but because it is old it was slightly rusted. When he turned the fan on it spun very slow, struggling to move. He then decided to lubricate the bearing that rotates the fan blades and the fan started spinning normally.

Question: Will reducing the friction in a machine make the machine require more or less work?
Answer: less

Situation: During the summer Anthony found it was way too hot to be comfortable. He went out to his garage to get an old fan. The fan was spins on a metal bearing but because it is old it was slightly rusted. When he turned the fan on it spun very slow, struggling to move. He then decided to lubricate the bearing that rotates the fan blades and the fan started spinning normally.

Question: Given a rusted machine and a freshly lubricated machine, which one will require less work to operate, the rusted one of the lubricated one?
Answer: lubricated machine

Situation: During the summer Anthony found it was way too hot to be comfortable. He went out to his garage to get an old fan. The fan was spins on a metal bearing but because it is old it was slightly rusted. When he turned the fan on it spun very slow, struggling to move. He then decided to lubricate the bearing that rotates the fan blades and the fan started spinning normally.

Question: Given that Adam decided to tighten the bearing in his fan will the work it requires to operate increase or decrease?
Answer: increase

Situation: During the summer Anthony found it was way too hot to be comfortable. He went out to his garage to get an old fan. The fan was spins on a metal bearing but because it is old it was slightly rusted. When he turned the fan on it spun very slow, struggling to move. He then decided to lubricate the bearing that rotates the fan blades and the fan started spinning normally.

Question: Given a lawn mower with a rusted blade, will it reqiore more or less work to operate than one with a normal blade?
Answer: more