11. Newton's Laws of Motion
Success Criteria
Your learning has been successful if you can do the following:
Define acceleration and its units.
Calculate acceleration from speed and time measurements.
Vocabulary
Learn these so you can communicate this concept well.
Average speed: Calculated by the total distance travelled divided by the total time taken for the journey.
Gradient / slope: How steep a line on a graph is.
Speed: How fast an object is moving.
Velocity: Similar to speed, but also tells us the direction in which an object is moving. It includes both speed and direction of motion.
Do Now:
Collect and complete this small 'Do Now'. Then glue into your SciPAD page 11. Use your commonsense when glueing - don't glue straight on-top of words!
Find some space on page 15 of your PESS1.2 SciPAD,
and answer the following questions:
What does each letter in CUTLASS stand for?
Isaac Newton's Laws of Motion
Sir Isaac Newton laid out the fundamental ideas governing the behaviour of objects in motion. These ideas have been tested and verified so many times by so many scientists over the years that they are no called Newton's Laws of Motion.
The First Law of Motion
The first law of motion states that objects at rest stay remain still, while those in motion continue moving in the same direction and speed unless acted upon by an unbalanced force.
Once a car starts moving, it keeps going unless the driver presses the brake pedal or the road gets bumpy, slowing it down.
If you push a book on a table, it slides until something, like your hand or a wall, stops it. If you slide it gently, it keeps moving for a while before stopping.
An ice skater gliding on ice keeps moving until they stop theselves or something like a rough spot on the ice slows them down.
When you fly a kite, it stays up because the wind pushes against it. If the wind stops or changes direction, the kite might float down or fly in a different direction.
A parked car will not move by itself. It needs someone to push the gas pedal or pull it with a tow truck to start moving.
The Second Law of Motion
The second law of motion states that the acceleration of an object, caused by a total applied force, is directly proportional to the force's magnitude and direction, and inversely proportional to the object's mass.
Basically...
When you push a shopping cart with more force, it accelerates faster. If the cart is empty (less mass), it's easier to push and speeds up quickly (more acceleration). But if it is full with groceries (more mass), you have to push harder (more force) to make it move as fast.
When you kick a soccer ball lightly, it doesn't go ver far. But if you kick it with more force, it travels farther because the force you kick makes it accelerate faster.
When you pedal harder on your bike, you go faster. It's easier to pedal on a flat road, but if you're going uphill, you have to push harder to keep moving at the same speed.
When you swing your legs to go higher on a swing, you're using Newton's second law. By pushing harder against the seat, you accelerate and go higher.
When you throw a ball gently, it goes very far. But if you throw it with more force, it goes farther because the force makes it accelerate more.
The Third Law of Motion
The third law of motion states that every action has an equal and opposite reaction. Forces always occur in pairs.
When you walk, your foot pushes backward against the ground (action), and the ground pushes forward against your foot (reaction), propelling you forward.
When you bounce a ball, you push it down onto the ground (action), and the ground pushes the ball back up (reaction), causing it to bounce back into your hand.
As you swim, you push the water behind you with your arms and legs (action), and the water pushes you forwward (reaction), allowing you to move through the water.
When you row a boat, the oars push against the water (action), and the water pushes the boat forward (reaction), propelling it through the water.
When you fly a kite, the wind pushes against the kite (action) and the kite pulls back against the wind (reaction), allowing it to stay in the air.
