Work

Work

What is work to you. Write on your own page answering the warmup question.

Work

• Work is done when a force is applied to an object and the object moves in a direction of the applied force.

• Force x distance is the simplest way to define work

• This is measured in a Joule

• Have you heard of Joules before?

Multiple Choice

What must happen for work to have been done?

• movement

• force applied

Multiple Choice

A weightlifter moves 120 kg to an overhead position in the jerk portion of his lift he moved through a distance of .35 m to complete the lift. How much work has been done?

• 411.6 J

• 42 J

• 4.3 J

• 1176 J

Multiple Choice

Does speed of an object have any effect on how much work is done?

• Yes

• No

Open Ended

Give your reasoning for the previous answer.

Open Ended

Based on what we have done in the past do you think angles have any bearing on how much work is done?

Work

• If you said yes to the previous question you would be right. Much like with forces angles need to be factored in

• Also much like net forces work can be negative, positive, or zero

• They also can be added

Work Extra practice- should time allow

• You slide a .12 kg coffee mug .15m across a table. The force you exert is horizontal and of magnitude .10 N. The coefficient of kinetic friction between the mug and the table is .05 . How much work is done on the mug

• A farmhand pushes a bale of hay 3.9 m across the floow of a barn. She exerts a force of 88 N at an anle of 25 degrees below the horizontal

• To move a suitcase up to the checkin stand at an airport, a student pushes with a horizontal force through a distance of .95 m. If the work done by the students is 32 J, what is the magnitude of the force he exerts?