F.2 maths (area of circle) 10marks

Circumference of the tape = 3m / 16 = 300cm/16 = 75/4 cm
Circumference = pi x d
75/4 = pi x d
d = (75/4)/pi
d = 5.968cm (corrected to 3 sig. fig.)
d = 6cm (corrected to the nearest cm)//

2.
the speed of the car is 80km/h = 80000m/3600s = 200m/9s
for each second, it goes for (200/9)m
The circumference of the wheel = 0.35 x 2 x pi = (0.7pi)m
The number of revolutions made per second = (200/9) / (0.7pi) = 10 revolution//(corrected to the nearest integer.)

1.
A roll of circular adhesive tape falls onto the ground. It rolls for 3m and makes 16 revolutions. What is the diameter ( in cm) of the adhesive tape?

2.
The radius of each wheel of a car is 0.35m. If the car travels at a speed of 80 km/h, how many revolutions does each wheel make per second? ( Give the answer correct to the nearest integer.)

1.
It rolls 16 revolution for 300cm
which means 75/4cm per revolution.

We got a formula, 2nr = circumference
2nr = 75/4
2r = 75/4n cm
therefore, the diameter is 75/4n cm

where 2r is diameter and n is 180degree(pire).

2.
The circumference of the wheel is 0.35 x 2 x n = 0.7n
Speed of the car in meter is 80/3.6 = 200/9 m/s
The car travel 200/9m in a second.
It will make 0.7n/(200/9) = 10.105 revolutions/s
therefore, each wheel will make 10 revolution in a second.

where n is 180degree(pire).