# 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)