7.1 Forces
What is a force
An interaction between 2 objects
is friction a contact or non-contact force?
what is a gravitational field?
the area in which gravity acts
ends of a magnet are called....
poles
what is a simple machine
a device that makes a job easier to do
who "discovered" gravity and how?
isaac newton; apple fell on his head
if i am running to the left, which way is friction acting and between what 2 objects is it acting?
right; between ground and shoes
what has gravity?
anything with mass
static electricity is...?
when an object builds up charge within it
what do you call the gear at the start of a gear train?
driving gear
what is acceleration
the rate at which something speeds up
what is traction?
grip
draw gravitational field lines for earth
xx
do magnetic field lines flow from north to south or south to north?
north to south
third-class
balanced vs unbalanced forces
forces in opposite directions are equal and the object is at a constant velocity. Unbalanced means one side has a stronger force and the object is moving in that direction
what are the 2 factors influencing friction
how rough surfaces are and how hard they are pushed together
weight vs mass
mass is how much matter somehting has and weight is the how much gravity pulls on that mass
what 3 elements are magnetic?
iron, cobalt, nickel
what are the 3 different ways simple machines work?
change size of a force, make things speed up, change the direction of a force
what is inertia and give an example
the tendency of an object to resist change in its motion. When you suddenly stop a car and you jerk forward
2 examples on how to reduce friction
wheels, lubricants, streamlined shape to reduce air resistance, stop contact between objects
how is a stronger field represented using field lines?
density of the lines
conductors allow electrons to freely flow through them whereas insulators don't
what is a first-class lever
effort - fulcrum - load