Might not see or hear something until later Y Stopping Thinking Braking Y Bigger mass means more kinetic energy which takes longer to transfer to heat using friction. Y Y Speed = distance / time Might not see or hear something until later Y Y Affects the speed that our brain processes signals Y Converts kinetic energy to heat at a slower rate Y Reduces friction Y Reduces friction

It has size but no direction. Collect a range of different surfaces of similar size. Connect the block to a force-meter, place the block on top of the first surface and a 500g mass on top of the block to ensure good contact between the block and the surface. Pull the block across the surface and record the force required to get it moving. Repeat until you get 4 concordant results then repeat for the other surfaces. size direction 1200kg p=mxv 5m/s p= 1200 x 5 It has size but no direction. 6000 kgm/s

line the same total collision p=mxv p=mxv v=p/m p=12 000 x 1.5 12 000kg 27 000kg v=p/m p=12 000 x 1.5 1.5 m/s v=18000/27000 18000 kgm/s 18 000 kgm/s 0.67 m/s

zero low high All of these active safety features work by increasing the collision time, this reduces the collision force and reduces injuries to the driver and passengers. An accelerometer is attached securely to the trolley, using sellotape. Bubble wrap is used to create crumple zones of different thicknesses that are attached to the front of the trolley one at a time. The car is rolled down a ramp of specific height, length and steepness and crashed into a pile of textbooks that is kept the same for each test. The deceleration from the accelerometer could be used to calculate the force on the trolley using F=mxa

0 m/s F=(v-u)/t 5 m/s F=(0-5)/0.1 0.1s -50 N F=(v-u)/t 1 m/s N Ft=v-u E=Fxd 150N E=150x30 12 000kg 0 m/s F=(v-u)/t 4500 J 5 m/s F=(0-5)/0.1 0.1s -50 N E=Fxd 30m E/d=F 0.2 kg F=(v-u)/t F=6000/30 6000J 1 m/s 200 N Ft=v-u 0.0005s -(Ft+v)=u 100N u=-(100x0.0005+1) Half – Work done = force x distance moved, the force stays the same but the distance is half, so she would do half as much work. -1.05 m/s

50 000J – She has converted her GPE into Kinetic Energy. watts W Work done Power = Work Done / Time taken

P=E/t 7.2x104J GPE=mgh J 10s P=7.2x104/10 W 75kg GPE=mgh 200m 10N/kg GPE=75x10x200 10N/kg P=E/t 1.5x105 J Pxt=E 120s 1.5x106W E=1.5x106x120 1.8x106 J 4.0x105kg GPE=mgh GPE/mg=h 10N/kg h=2.0x1010/(4.0x105x10) E=Fxd 2.0x1010kg 5.0x103 m E=6400x1.3x105 1.54x105W 8.32x106 J GPE=mgh 6400 N P=E/t 1.2m GPE/gh=m 1.3x105m t=E/P m=8.16/(10x1.2) 10N/kg t=8.32x106/1.54x105 8.16J 0.68 kg 9.85x108 s

gravitational potential KE=½mv2 J gravitational potential 4000 kinetic 300kg KE=½mv2 15m/s KE=½x300x152 33750 J 8.16J KE=½mv2 8.16J √(2KE/m)=v 0.68kg KE=½mv2 200kg √(2x8.16/0.68)=v √(2KE/m)=v 4.90 m/s √(2x33750/200)=v 33750 18.4 m/s

1000kg KE=½mv2 1000kg KE=½mv2 15m/s 30m/s 8000N 8000N KE=½x1000x152 The amount of kinetic energy depends on v2. Doubling the velocity, requires 4x the energy. Having 4x the energy will require 4x the distance to stop. 112 500 J 450 000 J E=Fxd E=Fxd 8000N 8000N E/F=d E/F=d 112500/8000=d 450000/8000=d 14.06 m 56.25 m