1. 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

2. 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

3. 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= x 1.5
1.5 m/s
v=18000/27000
18000
kgm/s
kgm/s
0.67
m/s

4. 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

5. 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=-(100x )
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

6. 50 000J – She has converted her GPE into Kinetic Energy.
watts W
Work done
Power = Work Done / Time taken

7. 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

8. 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

9. 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. J 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