What do certain lines mean on velocity-time graphs?
- Straight horizontal line indicates constant velocity
- Straight uphill line (positive gradient) indicates constant acceleration.
- Straight downhill line (negative gradient) indicates constant deceleration.
What is newton’s first law?
An object will remain at rest or continue to travel with constant speed, and in the same direction, unless acted upon by an unbalanced force.
What is newton’s second law?
The acceleration of a body is proportional to the unbalanced force acting upon it and inversely proportoional to the object’s mass.
F=ma
What is newton’s third law?
If object A exerts a force on object B, then object B exerts an equal and opposite force on object A.
What does a person sitting on a chair mean?
The person exerts a force on a chair and the chair exerts and equal but opposite force on the person.
What does a chair that a person is sitting on mean?
The chair exerts a force on the Earth, and the Earth exerts an equal but opposite force on the chair.
How does free falling out of an aeroplane work?
- Object accelerates due to gravity.
- Weight is equal and opposite to air resistance when it reaches terminal velocity.
- Obect falls at a constant velocity.
What are the key concepts for projectile motion?
- An object’s horizontal velocity is constant.
- An object’s vertical acceleration is constant (gravity).
How can the horizontal/vertical distance be calculated from graphs?
- The area under Vh - t graphs can be used to calculate the horizontal distance travelled.
- The area under a Vv - t graph can be used to calculate the vertical distance fallen.
How do satellites behave as projectiles?
- The surface of the Earth curves away from them at the same rate as they fall.
- It has a constant horizontal velocity, constant vertical acceleration and constant altitude.
- Weight is the only significant force acting. The force changes the direction of vertical velocity, bending the straight-line path into curved orbit.
