5. Forces

Question 1

To stretch, bend or compress an object,

Answer 1

more than one force has to be applied

Question 2

Force

Answer 2

A push/pull exerted by one object onto another

Question 3

Elastically deformed

Answer 3

Returns to og shape when force removed

Question 4

Inelastically deformed

Answer 4

Won’t return to og shape when force removed

Question 5

Principle of moments

Answer 5

For an object to be in rotational equilibrium (balanced), the sum of all clockwise moments must be equal to the sum of all anticlockwise moments

Question 6

Lever

Answer 6

A tool that gives a mechanical advantage

Question 7

Gear

Answer 7

Circular discs interlocking to transmit rotational motion.
The smaller the gear, the faster it rotates.
Varying the output force based on the ratio of the number of teeth.

Question 8

If a fluid is heated, why does pressure increase?

Answer 8

Particles gain Eke
Particles collide with walls more frequently
Particles exert a greater force in each collision

Question 9

How does a hydraulic system act as a force multiplier system?

Answer 9

Question 10

Upthrust

Answer 10

When the pressure from below an object is larger than the pressure from above, the resultant force is upthrust.

Question 11

Floating

Answer 11

Upthrust = Weight

Question 12

Sinking

Answer 12

Upthrust < Weight

Question 13

Density and upthrust

Answer 13

If the density of the object is lower than the fluid, then only part of it must be submerged for it to float.

Higher density - More submerged

If the density of the object is higher than the fluid, it will never displace enough fluid to equal weight

Question 14

Acceleration

Answer 14

Increase V
Decrease V
Change direction

Question 15

Newton’s First Law

Answer 15

If the resultant force on an object is 0, that object will continue to move at a constant velocity

Therefore: If an object experiences a resultant force, it will accelerate in the direction of the resultant force.

Question 16

Inertia

Answer 16

The tendency of an object to remain at its’ current velocity

Question 17

Newton’s Second Law

Answer 17

The acceleration of an object:

• Directly proportional to resultant force
• Inversely proportional to inertial mass

Question 18

Newton’s Third Law

Answer 18

If body A exerts a force on Body B, then Body B will exert an EQUAL and OPPOSITE force of the same type.

Question 19

Walking

Answer 19

1.5m/s

Question 20

Running

Answer 20

3m/s

Question 21

Cycling

Answer 21

6m/s

Question 22

Car

Answer 22

25m/s

Question 23

Train

Answer 23

55m/s

Question 24

Plane

Answer 24

250m/s

Question 25

Sound

Answer 25

340 m/s

Question 26

Light

Answer 26

300 000 000 m/s

Question 27

Terminal velocity

Answer 27

initially air resistance is less than weight / gravity so the skydiver accelerates acceleration causes the air resistance to increase resultant force decreases to zero so the skydiver falls at terminal velocity (no resultant force, as forces are equal in magnitude) RESULTANT FORCE IS UPWARDS OBJECT ACCELERATES UPWARDS AS SURFACE AREA OF PARACHUTE CAUSES AIR RESISTANCE TO INCREASE -> VELOCITY DECREASES -> AIR RESISTANCE DECREASES (FEWER COLLISIONS PER SECOND)

Question 28

Stopping

Answer 28

Thinking + Braking

Question 29

Thinking distance

Answer 29

Reaction time Speed

Question 30

Reaction time

Answer 30

Distractions reducing concentration up Tiredness up Drugs up or down Alcohol up

Question 31

Braking distance

Answer 31

Speed Quality of brakes Quality of tyres Surface conditions Road going downhill Increased mass of passengers

Question 32

Braking energetics

Answer 32

When brakes pads push on wheels, transfers energy mechanically via friction Decreases wheel's eke Increases thermal store Therefore: If deceleration too high, overheating means driver loses control of vehicle. Therefore: Maximum braking force

Question 33

Conservation of momentum

Answer 33

Eeeuuhh momentum is always conserved 💯

Question 34

Car safety 🐈

Answer 34

Increasing time taken for the collision, for the same change in momentum. This decreases the force experienced.

Question 35

6 marks: man in car man crashes car man wearing seatbelt car (🐈) forgor 💀 what happens to the 🚗 and the 🐈 and the 🕴

Answer 35

🚗 experiences a force against its' motion and decellerates 🚗 stops 🕴 continues moving @ high speed 🕴 increases time for collision, stopping him w less force than the car 🐈 continues moving @ high speed 🐈 hits windscreen where it experiences a force and comes to rest (in peace) (and pieces)