can sum1 do this (1 Viewer)

[taco man]

I dont understand wat this question is saying, can someone do this for me plz

Find correct to 3 decimal places, the angle in radians through which:
a) the second hand of a clock turns in 7 seconds
b) the hour hand in of a clock turns between 6am and 6.40am



thanks

 

[shafqat]

I dont understand wat this question is saying, can someone do this for me plz

Find correct to 3 decimal places, the angle in radians through which:
a) the second hand of a clock turns in 7 seconds
b) the hour hand in of a clock turns between 6am and 6.40am



thanks

The hands of a clock rotate in a circle. There are sixty seconds in one revolution, and hence the second hand turns 360/60 = 6 degrees every second. So in 7 seconds it turns 42 degrees. Then convert into radians. Use the same reasoning for part (b).

 

[sunjet]

Not sure but,

(a) In 7 seconds it goes 42degrees (5seconds = 30degrees, 60 seconds = 360 degrees)

42 . PIE / 180
= 7PIE / 3

 

[who_loves_maths]

Originally Posted by taco man
I dont understand wat this question is saying, can someone do this for me plz

Find correct to 3 decimal places, the angle in radians through which:
a) the second hand of a clock turns in 7 seconds
b) the hour hand in of a clock turns between 6am and 6.40am

hi taco man,

Part (a):

60 seconds makes up one revolution of the second hand. in one revolution there are 2pi radians.

every second is equally spaced around the clock face, hence, a one second gap has angle: 2pi/60 = pi/30 radians.

so through 7 seconds, the second hand travels (pi/30)*7 = 7pi/30 radians = 0.733 radians to 3 dec. pl.

Part (b):

from 6am to 6:40 am, exactly 40 minutes passes. now if exactly one hour passes, then the hour hand will move exactly 5 spaces ahead, and 5 spaces equates to exactly 5*(pi/30) = pi/6 radians.

but 40 minutes is not one hour. instead, 40 minutes is 40/60 = 2/3 of an hour.

hence, the hour hand moves in total through (2/3)*(pi/6) = pi/9 radians = 0.349 radians to 3 dec. pl.


hope that helps

 

[zahid]

I dont understand wat this question is saying, can someone do this for me plz

Find correct to 3 decimal places, the angle in radians through which:
a) the second hand of a clock turns in 7 seconds
b) the hour hand in of a clock turns between 6am and 6.40am



thanks

aaah yes if i am not mistaken thats from the cambridge 2u book.

 

[taco man]

aaah yes if i am not mistaken thats from the cambridge 2u book.

u are mistaken it was from the cambridge 3u book

 

[zahid]

oops....looks like its in the 2u one aswell.