Forces 1.

Target Language or Knowledge:

Effects of Forces:
Force are _pushes,_ pulls or twists. _ Hitting_ a ball is an example of a push force. Towing a car is an example of a _pull_force._ Forces can have different effects. _ speed_up_ an object _ slow_ down an object _ change_the_direction_ of motion _ squash_ (or stretch) an object
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The size of a force is measured in units called _newtons,_ symbol N. When you apply a force to a free object it will _accelerate_ in the direction that the force pushes or pulls it. If you increase the size of that _force,_ then the object's acceleration will be greater. _ Doubling_ the force on an object that is free to move will cause its _acceleration_ to double.
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If the object causing the force needs to _touch_ the object it acts on (e.g. a hockey stick striking a ball), then the force is called a _contact_ force. Other forces can act over a _distance_ without requiring contact between the _object_ creating the force and the object it acts on (e.g. a magnet attracting a paper clip). These forces are called _non-contact_ forces.
Match the pairs below:
force associated with a magnetised object → magnetic force, object causing force must touch object it acts on → contact force, caused by the gravitational pull of Earth → force of gravity, force associated with a charged object → electrostatic force
Forces have both
magnitude and direction.
A force that sets an object into motion is
unbalanced.
The distance traveled by an object per unit time is called
speed.
Velocity is a measure of speed that takes into account the
direction of movement.
If you speed up from rest to 12 m/s in 3 seconds, what is your acceleration?
4 m/s/s
A force that makes objects pull toward each other is known as .
gravity
A toolbox falls off a roof and does 147 Joules of work falling 3 meters to the ground. What was the mass of the toolbox?
4.9 kg
Weight is a measure of .
the gravitational attraction between you and Earth
An object of mass 10 kg is accelerated upward at 2 m/s2. What force is required?
20 N
A 20 kg bike accelerates at 10 m/s2. what was the force?
200 Newtons
A 10-kg ball is accelerated 500m/s (squared) by a force of...
5000 N
What is the resultant force of the two forces shown opposite?
110 N (to the right)
1. What is the resultant force of the two forces shown opposite?
10 N (to the right)
Sarah pulls on one end of a rope with a force of 100 N, and her friend Jane pulls on the other end with a force of 100 N. What happens to the rope and why?
It doesn't move at all because the resultant force is zero.
Which 2 statements could best describe an object's motion when the resultant force is 0 N?
Constant velocity, Stationary