Page 81 - CT&AI_CLasa_7_Part_1

4. Three students each hold a pendulum of the block aligns with the 8.5 cm mark, what is
identical length (50 cm) but with different bob the actual length of the block?
weights: 50 g, 100 g, and 200 g. They each (Pattern Recognition)
count 10 complete oscillations and record the
time as shown in the given table. All readings (a) 8.5 cm (b) 10.5 cm
are nearly identical. Farida claims: 'Heavier
bobs swing faster — C should take the least (c) 6.5 cm (d) 6.0 cm
time.'
6. A pendulum is swinging in a room. If you pull
Weights Time
the "Bob" slightly further to the side before
Student A 50 g 22.1 s letting go, but do NOT change the length of
Student B 100 g 22.3 s the string, what happens to the Time Period?
Student C 200 g 22.0 s (Algorithmic Thinking)

(a) The Time Period increases because
it has further to travel.

(b) The Time Period decreases because
it moves faster.

(c) The Time Period stays constant
50g
100g
200g because the length of the string has
not changed.
Why are all three time periods nearly equal,
and what does this tell us about what actually
controls a pendulum's time period? (d) The pendulum will stop swinging
immediately.
(Decomposition)
7. The driver covered 40 km in 2 hours, resulting
(a) Farida is correct — heavier bobs in an average speed of 20 km/h. Imagine the
swing faster due to gravity pulling driver stopped for a 30-minute coffee break
harder.
exactly at the halfway point, but still arrived
(b) All are nearly equal because the at his destination in exactly 2 hours total. How
time period of a pendulum depends does this break affect the overall average
on its length, not the mass of the speed for the entire journey?
bob — all three pendulums have (Pattern Recognition)
the same length.
(a) The overall average speed
(c) All are equal because the students increases.
made measurement errors.
(b) The overall average speed

(d) Time period depends on the decreases.
material of the bob — all three are (c) The overall average speed remains
the same material.
the same because the total time
5. Rahul is measuring a wooden block. The (2 hours) is unchanged.
zero mark on his ruler is broken, so he starts
measuring from the 2 cm mark. If the end of (d) Average speed cannot be
calculated if there is a break.

Measurement of Time and Motion 79