Answer:
1. Find the circumference, then multiply that by 120 turns.
Formula for circumference;
C = 2πr
But, we need to find the radius which is 1/2(half) of the diameter, so,
D/2 = R
D = Diameter
R = Radius
20/2 = 10 is the radius.
Plug in values now:-
C = 2(3.14) x 10
C = 6.28 x 10
C = 62.8 is the circumference, now we multiply this by 120 to get the total amount of centimetres it'll go.
62.8(120)
= 7,536 cm it'll go.
2. Find the circumference, then multiply that by 750 turns/revolutions.
C = 2πr
Find radius,
D/2 = R
50/2 = 25 is the radius.
Plug in values now:-
C = 2(3.14) x 25
C = 6.28 x 25
C = 157 cm it'll go.
3. Same thing, find circumference then compare values.
Given that radius is 10,
Use the formula for circumference;
C = 2πr
Replace values:-
C = 2(3.14) x 10
C = 6.28 x 10
C = 62.8 cm is the circumference of the first circle.
Now the second circle, (use same formula)
C = 2πr
Find radius,
D/2 = R
10/2 = 5 is the radius.
Replace values:-
C = 2(3.14) x 5
C = 6.28 x 5
C = 31.4 cm is the circumference for the second circle.
Now subtract the second circle's circumference from the first:
62.8 - 31.4
= 31.4, 31.4 cm is how much greater the second circle is than the first.
4 - 5. Find circumference, (using circumference formula)
C = 2πr
Find radius,
D/2 = R
760/2 = 380
Replace values:-
C = 2(3.14) x 380
C = 6.28 x 380
C = 2,386.4 km is the distance he'll travel.
If he wants to travel around it with 2,000 km, he'll need to travel at least once.