Forces

Question 1

scalar =

Answer 1

a quantity that only has magnitude

Question 2

vector =

Answer 2

a quantity that has both magnitude and direction

Question 3

Weight is a force due to ….

Answer 3

gravity

Question 4

Friction is a force due to ….

Answer 4

moving surfaces rubbing

Question 5

Electric forces exist between …

Answer 5

two charged objects

Question 6

Magnetic forces exist between …

Answer 6

two magnetic objects

Question 7

Tension is a ….

Answer 7

stretching force

Question 8

Thrust (engine force) is a force produced by an ….

Answer 8

engine

Question 9

Drag is a force due to

Answer 9

air resistance

Question 10

Upthrust is a

Answer 10

floating force

Question 11

Reaction is the force produced by

Answer 11

the surface than an object rests on

Question 12

Resultant force =

Answer 12

a single imaginary force that is equivalent to all forces acting on an object, equal to mass x acceleration

Question 13

Friction =

Answer 13

force that opposes motion

Question 14

Resultant force (N) =

Answer 14

mass (Kg) x acceleration (m/s**2)

Question 15

Weight (N) =

Answer 15

mass (Kg) x gravity (N/Kg)

Question 16

Force is measured in

Answer 16

N

Question 17

Acceleration is measured in

Answer 17

m/s**2

Question 18

Gravity is measured in

Answer 18

N/m

Question 19

Mass is measured in

Answer 19

Kg

Question 20

Stopping distance =

Answer 20

The distance taken to stop the vehicle

Question 21

Thinking distance =

Answer 21

The distance taken for a diver to react to a situation

Question 22

Braking distance =

Answer 22

The distance taken to stop once the brakes are applied

Question 23

Stopping distance (m) =

Answer 23

thinking distance (m) + braking distance (m)

Question 24

Examples of Thinking Distance :

Answer 24

• Concentration (Tiredness)

* Intoxication (Alcohol/Drugs)

Question 25

Examples of Braking Distance :

Answer 25

• Weather conditions

* Road conditions

Question 26

Drag / weight ∝

Answer 26

terminal velocity

Question 27

Examples of Scalar:

Answer 27

• distance
• speed
• time
• power
• energy

Question 28

Examples of Vector :

Answer 28

• displacement
• velocity
• acceleration
• force
• weight
• momentum

Question 29

When the result force is zero, the object is either …

Answer 29

travelling at a constant speed or is stationary the object is either travelling at a constant speed or is stationary

Question 30

When the resultant force is positive, the object will be …

Answer 30

accelerating in the direction of the resultant force, (usually right)

Question 31

When the resultant force is negative, the object will be decelerating

Answer 31

in the direction of the resultant force, (usually left)

Question 32

Explain the motion of a parachutist in terms of resultant force, drag and weight : before the parachute opens

Answer 32

1) When the skydiver jumps out of the plane he ACCELERATES due to the force of GRAVITY pulling him/her down
2) As he speeds up the upwards AIR RESISTANCE force increases. He carries on accelerating as long as the air resistance is LESS THAN the WEIGHT
3) EVENTUALLY he reaches TERMINAL SPEED, when the AIR RESISTANCE and WEIGHT become EQUAL. They’re said to be balanced

Question 33

Explain the motion of a parachutist in terms of resultant force, drag and weight : After the parachute is open

Answer 33

4) When the parachute opens, it has a large surface area which increases the AIR RESISTANCE. This UNBALANCES the forces and causes the parachutist to slow down
5) As the parachutist slows down, his air resistance gets less until eventually it equals the downwards force of gravity on him (his weight). Once again the two forces balance and he falls at terminal speed. This time at a much slower terminal speed than before