Forces and Energy Flashcards
(23 cards)
Complete the sentence: When a system changes, energy is………
transferred
Name 3 ways energy can be transferred.
By Heating, by forces doing work or by electrical equipment.
What is a closed system?
A closed system is one that’s defined so that the net change in energy is 0.
What is work done?
A force moving on an object.
What is the equation for work done?
E=Fd
Calculate the distance travelled in km if a 5kN force acts on an object with a work done of 15kJ
3km
What is power?
How much work is done per second
What is power measured in?
Watts (W)
What is the formula for Power?
P=E/t
Calculate the work done in mJ if a 650W microwave runs for 1.24hours.
2.9016mJ
What causes forces?
Interactions between objects.
Give an example of a non-contact force.
gravity
Give an example of a contact force.
Friction
What do free-body force diagrams show?
All the forces acting on an object
What is a resultant force?
The overall force on a point or object.
What is the resultant force of an object in equilibrium?
0
What is the resultant force of a car if the forward force is 5kN and the frictional forces are equal to 1400N?
3600N or 3.6kN
What 2 components can a force be split into?
horizontal and vertical
What is a moment?
The Turning effect of a force
What is the formula for moment
Moment=Force x distance normal to the direction of the force.
Calculate the moment if a 50cm long spanner is turned with a force of 6.5N.
3.25Nm
What do gears transmit?
Turning forces.
The larger the gear, does the speed that it spins increase or decrease.
Increase.
