5.2 Work Done and Energy Transfer

Question 1

what does it mean if a force is said to do ‘work’?

Answer 1

the force causes an object to be displaced through a distance.

Question 2

what is the equation used to calculate work done?

Answer 2

work done = force x distance
work done (joules), force (newtons), distance (metres)

Question 3

what distance must be used when calculating work done?

Answer 3

it must be the distance that is moved along the line of action of the force.

Question 4

how many newton-metres are equal to 1 joule of energy?

Answer 4

1 Nm = 1 J

Question 4

how much work is done by the force acting on the below object over a distance of 5m?
–10N–> object

Answer 4

10 x 5 = 50 Nm
= 50 J

Question 5

under what circumstance is 1 joule of work done?

Answer 5

when a force of 1 newton causes a displacement of 1 metre.

Question 5

what occurs when work is done against frictional forces?

Answer 5

• a rise in temperature of the object occurs
• kinetic energy is converted to heat

Question 6

why does air resistance slow down a projectile?

Answer 6

• the object does work against the air resistance
• kinetic energy is converted in to heat, slowing down the object