Flashcards in Knowing Relationships Deck (19)

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1

##
A ship is carrying out a survey of the sea bed using ultrasound waves. The speed of ultrasound waves in the water is 1500ms-1.

One pulse of ultra sound is received back at the ship 0.36 seconds after it was transmitted.

How would you calculate the depth of the sea bed?

###
d=vt

d = 1500 x 0.18

d = 270m

Help

( half 0.36 to get 0.18 )

2

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The frequency of the wave is 1200 and the waves are produced in 1 minute.

How would you calculate the Frequency?

###
f = N/ t

f = 1200/ 60

f = 20Hz

Help

( if you get 1 minute, convert into seconds)

( the dash ( / ) is divide )

3

##
A wave has a frequency of 50Hz.

How would you calculate the time period of the wave?

###
T = 1/f

T = 1/50

T= 0.02s

Help

( the top is always a 1 )

4

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The crest to trough height is 0.5m.

How would you calculate the amplitude?

###
Amplitude = 0.5/2 = 0.25

Help

( there is no formula )

( you always divide the number of waves by 2 )

5

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A wave can travel at 800m in one minute.

How would you calculate the speed of the wave?

###
d = vt

800 = v x 60

v = 800/60

v = 13.3ms-1

Help

( the first line of numbers is only to help you, unless you are working out the distance, in d =vt you always divide )

6

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A wave has a frequency of 500Hz and a wavelength of 0.5m.

How would you calculate the speed of the wave?

###
v = f λ

v = 500 x 0.5

v = 250ms-1

7

##
A car traveled 1.5km in 1 minute.

How would you calculate the average speed of the car?

###
d = ṽt

1.5 x 10 3 = ṽ x 60

1.5 ṽ x 10 3/ 60 = ṽ

ṽ = 25ms-1

Help

( 1.5km has been converted to 1.5 x 10 3 )

8

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Distance is the total that the cat has travelled 10m North then 3m South.

How would you calculate the distance on a vector quantity arrow?

### Distance = 10 + 3 = 13m

9

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A car is travelling at 14ms-1 and accelerated to 30ms-1 in 4 seconds.

How would you calculate the acceleration of the car?

###
a = v - u/ t

a = 30 - 14/ 4

a = 16/4

a = 4ms-1

Help

( you do not need to write a = 16/4 )

10

##
A car of mass 600g accelerated at 10ms-2.

How would you calculate the unbalanced force required for this acceleration?

###
F = ma

F = 600 x 10

F = 6000N

Help

( ms-2 means metres per second per second )

11

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A dog has a mass of 15kg.

How would you you calculate the mass and weight of the dog on earth’s surface and the moons surface.

( Earth g = 9.8Nkg-1 )

( Moon g = 1.6Nkg-1 )

###
W = mg

W = 15 x 9.8

W = 147N

W = mg

W = 15 x 1.6

W = 24N

Help

( look out for where the certain thing is. Eg. On earth or the moon )

( you will have a sheet provided with the gravitational field strengths )

12

##
A car is towed 150m along a road. A force of 2000N is applied.

How much work is done in moving the car?

###
Ew= Fd

Ew= 2000 x 150

Ew= 300,000J

13

##
A crane lifts a mental girder of mass 25kg through a height of 15m.

How would you calculate the potential energy gained?

###
Ep = mgh

Ep = 25 x 9.8 x 15

Ep = 36775J

Help

( if it does not tell you where the gravitational field strength is then automatically assume it’s earth )

14

##
A 650kg car is travelling at 12ms-1.

Calculate the kinetic energy of the car.

###
Ek = 1/2 mv2

Ek = 0.5 x 650 x 12 squared

Ek = 0.5 x 650 x 12 x 12

Ek = 46800J

Help

( times the velocity by itself )

( you don’t need to include the 3rd line )

15

##
A sample of body tissue has a mass of 0.5kg, if the energy absorbed by the tissue is 6.5J.

How would you calculate the absorbed dose?

###
D = E/m

D = 6.5 x 10-3/0.5

D = 1.3 x 10-2Gy

Help

( if your looking for prefix’s and it has kg, look for the first letter closet to the number eg. this would be ( k ) )

16

## What is the equivalent dose caused by alpha particles if the absorbed dose is 4.5 x 10-5Gy ?

###
H = DwR

H = 4.5 x 10-5 x 20

H = 9 x 10-4Sv

Help

( the wR is the radiation given, you will have a sheet giving you the numbers )

17

## What is the equivalent does rate caused by an equivalent dose of 100mSv of beta particles in 5 hours?

###
Ḣ = H/t

Ḣ = 100 x 10-3/18000

Ḣ = 5.55 x10-6Svs-1

Help

( 5 hours ( 5 x 60 x 60 seconds = 18000 )

18

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A Geiger counter records 1800 counts in a 90 second period.

What is the activity of the source?

###
A = N/t

A = 1800/90

A = 20Bq

19