P5 Flashcards
(24 cards)
What is a scalar quantity
Only has a magnitude
Vector quantity
Has a magnitude and direction
What is a contact force
Two objects have to be touching for a force to act
What is a non-contact force
The objects do not need to be touching for a force to act
What is a free body diagram
Shows all forces acting on an object via diagram
Describe all forces acting on an equilibrium
Balanced
What is the resultant force of an object or point
Overall force
What does elastically deformed mean?
Can go back to its original shape and length after force is removed
What does inelastically deformed mean?
DOESNT return to its original force and length after the force is removed
What is the limit of proportionality
When the line on a graph begins to curve at its maximum force
What is a moment?
The turning effect of a force
What does it mean if the total anticlockwise moment equals the total clockwise moment about a pivot
The object is balanced and wont turn
What does it mean when an object is more dense
More particles that are able to collide so the pressure is higher
What does it mean when an object floats?
Upthrust on an object is equal to the objects weight
What happens as altitude increases
Atmospheric pressure decreases
Explain why a wooden object (p=700 kg/m3) floats in water (p=1000 kg/m3).
Wood is less dense than water which means that when a wooden object is placed in water, it can displace enough water to create an upthrust equal to the weight of the object. So the upthrust equals the weight and it floats.
What is distance
How far an object has moved
How can you calculate the distance travelled with a constant speed
s = vt ->. Distance travelled=speed x time
How do you calculate displacement
Measure the distance and direction in a straight line from an objects starting point to its finishing point
What is acceleration
Change in velocity in a certain amount of time
How do you calculate uniform acceleration
final velocity^2 - initial velocity^2 = 2 x acceleration x distance
How do you calculate distance travelled in a time interval on a velocity-time graph
Area under section of graph
What is terminal velocity
When the resultant force is zero and can no longer speed up. Frictional force is equal to the acceleration force
Explain why a ball falling from the top of a tall building reaches terminal velocity
As the ball falls, it accelerates towards earth due to the force of gravity. Air resistance also acts on the ball, in the opposite direction to the force due to gravity. As the ball speeds ip, the air resistance increases until the accelerating force and the air resistance balance. The object cannot go any faster- this is its terminal velocity
