13. P8 Forces and Motion Flashcards
Frictional forces always ?.
oppose motion
What is the equation for Work done
Work done = Force x distance
If the forces on an object are balanced?
…it will stay at a constant velocity (same speed and direction) or at rest
What are the two things that a force does?
- Changes an object’s motion 2. Change an object’s shape
What is Hooke’s Law?
Force = spring constant x extension
Describe the forces if an object is not moving or not getting faster or slower.
The forces on it are balanced
What is the equation for Weight?
Weight = mass (kg) x gravitational field strength
Acceleration is?
when an object’s velocity (speed or direction) change
The equation for acceleration is ?
a = change in velocity / time taken
If an unbalanced force acts on an object?
it will cause an acceleration
Stopping distance =
Thinking distance + braking distance
What are the factors that affect Thinking distance?
Tiredness, drugs or alcohol, speed, distractions
The greater the force on an object that can’t move?
The greater the extension the force causes.
What are the factors that affect Braking distance?
Worn tyre or brakes, road surface (rain or ice), speed
The equation for accelerating force (Newton’s second law)
Force (Newtons) = mass (kg) x acceleration (m/s2)
The larger the Resultant (Overall) force on an object
The greater the acceleration
On a distance time graph the steeper the gradient
The faster the object is travelling
On a distance time graph a horizontal line means
The object is stationary
On a velocity time graph the steeper the gradient ?
The greater the acceleration
Forces acting in the same direction
Add to give the resultant force
Forces acting in opposite directions
Subtract to give the resultant force.
