forces and motion 2

Question 1

What is the SI unit for mass?

Answer 1

-Kg (kilograms)

Question 2

What is the SI unit for distance?

Answer 2

-m (meters)

Question 3

What is the SI unit for speed?

Answer 3

-m/s (metres per second)

Question 4

What is the SI unit for acceleration?

Answer 4

-m/s2 (meters per second squared)

Question 5

What is the SI unit for force?

Answer 5

-N (newtons)

Question 6

What is the SI unit for time?

Answer 6

-s (seconds)

Question 7

What is the SI unit for gravitational force constant?

Answer 7

-N/Kg (newtons per kilogram)

Question 8

What is the SI unit for spring constant?

Answer 8

-N/m (newtons per meter)

Question 9

What is newtons 2nd law?

Answer 9

-when there is a resultant force on a body it will accelerate

Question 10

What is the equation for force?

Answer 10

FORCE = MASS X ACCELERATION

Question 11

If there is a lefthand force of 200N on a car and a righthand force of 500N. Which way will the car go?

Answer 11

• 300N to the right

- +300N

Question 12

When there is a resultant force of 0. Which way is the car moving?

Answer 12

-it is stationary or constant velocity

Question 13

What is weight?

Answer 13

-a downwards force caused by gravity

Question 14

What is mass?

Answer 14

-the quantity of matter a body contains

Question 15

What is the equation for weight?

Answer 15

WEIGHT = MASS X GRAVITATIONAL FORCE CONSTANT

Question 16

If a box has a mass of 30Kg what is its weight?

Answer 16

30 x 10 = 300N

Question 17

The gravitational force constant on earth is …

Answer 17

-10N/Kg

Question 18

The acceleration of freefall on earth is …

Answer 18

-10m/s2

Question 19

What does drag do?

Answer 19

-Drag acts to OPPOSE the direction of motion

Question 20

What makes drag increase (2)?

Answer 20

• as velocity increases

- as surface area increases

Question 21

What is terminal velocity?

Answer 21

• when drag equals weight
• once they are equal the resultant force on the object is 0 which means acceleration is 0 also so the falling object can’t go any faster!

Question 22

What is momentum?

Answer 22

• the momentum of an object is the product of its mass and velocity
• momentum is a vector

Question 23

What is the equation for momentum?

Answer 23

MOMENTUM = MASS X VELOCITY

Question 24

What is the change in momentum?

Answer 24

-change in momentum is final momentum - initial momentum

Question 25

A train mass of 20 tonnes is travelling along a straight track at 10m/s as it passes Salisbury station. As it exits the town, its velocity increases to 60m/s. Calculate the change in momentum of the train.

Answer 25

-final momentum is 20 tonnes x 60 = | NOT FINISHED

Question 26

What is the equation for force?

Answer 26

-force = change in momentum ÷ time taken

Question 27

What is the conservation of momentum?

Answer 27

-MOMENTUM BEFORE = MOMENTUM AFTER!!!!!!!!!!!

Question 28

Two snooker balls (mass=0.5Kg) collide. Initially ball 1 is moving with velocity +5m/s ball 2 is moving with velocity -1m/s after collision ball 2 is moving with velocity +3m/s What is the velocity of ball 1???

Answer 28

-mom. before = (0.5(m) x 5(v)) + (0.5(m) x -1(v)) = 2.5+0.5 = 2Kgm/s ``` -mom. after(mom before) = 2(mom)= (0.5(m) x v) + (0.5(m) x 3(v)) = 2 = (0.5(m) x v) + 1.5 = 2-1.5 = 0.5 x v (0.5 = 0.5 x v) = v = 1m/s ```

Question 29

What is stopping distance?

Answer 29

-thinking distance + braking distance

Question 30

Factors that affect braking distance?

Answer 30

- the condition of tyres - mass of the vehicle - snowy/wet road - speed - driving downhill

Question 31

Factors that affect thinking distance?

Answer 31

- drinking and other drugs - distracted by music or phone - tiredness - speed

Question 32

What are airbags used for?

Answer 32

- to increase speed | - and hence reducing the force

Question 33

Where does weight act through in/ on a body?

Answer 33

The weight of the body acts through its centre of | gravity

Question 34

What is the equation for a moment(force of moment)?

Answer 34

-the force of moment = force x distance from pivot