Energy
An object in motion tends to stay in motion and an object at rest tends to stay at rest unless acted upon by an unbalanced force.
Newton's first law of motion
Calculate the KE of a 1kg magpie flying at a speed of 15m/s
112.5J
A racehorse that wins the 3200m Melbourne Cup in a time of 3 min 20 sec- what is it's speed (answer in m/s)
16 m/s
While traveling along a highway a driver slows from 24 m/s to 15 m/s in 12 seconds. What is the automobile’s acceleration in m/s/s?
= distance/time
Speed/Velocity
For every action there is an equal and opposite reaction.
Newton's Third law of Motion
4.6kg baby Stevie is pushed in a pram at a speed of 3m/s. What is the KE?
20.7J
A kangaroo fleeing a dingo which bounds a distance of 2.5 km in 3 min (answer in m/s)
13.89m/s
A skater increases her velocity from 2.0 m/s to 10.0 m/s in 3.0 seconds. What is the skater’s acceleration?
2.67 m/s/s
= m x g xh
Potential energy (PE)
F = ma
Newton's second Law of Motion
82kg Fred is standing on the top of a 4.5m ladder.What is his potential gravitational energy? (Gravity - 9.8N/kg)
3616.2 J
A dolphin which keeps up with a boat for a distance of 2km for a time of 3 min (answer km/h)
40 km/h
A parachute changes the speed of the drag car from 85 m/s to 45 m/s in a period of 4.5 seconds. What is the acceleration of the dragster?
I-8.89m/s/s
F = m x a
Newton's Second Law
Also called the Law of Inertia
Newton's First Law of Motion
A paint can with a mass of 400g sits on the top of a 2.2 m fence. Calculate it's gravitational PE (Gravity 9.8N/Kg)
8.624J
Keirin Perkins as he completes the 1500m in a time of 15 min (answer in km/h)
6km/h
A cart rolling down an incline for 5.0 seconds has an acceleration of 4.0 m/s2. If the cart has a beginning speed of 2.0 m/s, what is its final speed?
22m/s
= change in speed / time
Acceleration (m/s/s)
An object's resistance to a change in its motion
Inertia
A construction worker is 12 metres above the gound and has 8200J of gravitational PE. What is his mass in Kg? (Gravity 9.8N/Kg)
69.73Kg
How long would it take you to walk from Melbourne to Sydney, a distance of 900 km, if you walked 5km/h without stopping. Answer in days
7 and 1/2 days
A car traveling at a speed of 30m/s encounters an emergency and comes to a complete stop. How much time will it take for the car to stop if it decelerates at -4.0 m/s2?
7.5s
1/2 x m x v2
Kinetic energy (KE)