4.5.6.2.1 Newton's First Law Flashcards
Newton’s First Law:
If the resultant force of an object is zero:
- if the object is stationary, it will remain stationary
- if the object is moving, it will continue to move at the same speed
When a vehicle travels at a steady pace what do the resistive forces do?
- when a vehicle travels at a steady pace the resistive forces balance the driving force
- so the velocity (speed and/or direction) of an object will only change if a resultant force is acting on the object)
Free body diagram for throwing a ball up in the air:
- ball gradually decelerates when thrown
- the ball is stationary at its highest point in the air
- it falls back down
- if an object is moving it doesn’t have to have a propelling force
Free body diagram to show pushing a ball at a constant speed:
thrust is mainly used for objects with an engine that’s why push is used
Free body diagram to show a tennis ball thrown over a fence:
What forces can stationary objects have acting on them?
- stationary object can have no forces acting on them as long as you’re far away from everything as there are forces only when two objects interact with each other
What forces might objects moving at a steady speed and direction have acting on them?
objects moving with a steady speed and direction have balanced forces i.e. there is no resultant force
What forces would an object with a constant velocity need acting on them?
- if an object is moving forward with a constant velocity it needs a force to keep it moving on Earth otherwise it would eventually come to a stop due to frictional forces
- however, in space it would carry on moving at a constant velocity as there would be no frictional forces as long as it is far away from all objects
Inertia:
the tendency of objects to continue in their state of rest or of uniform motion is called inertia
