NCERT Solutions for Class 7th Maths Chapter 2 Try This — A Quick Recap of Integers
Book page 27 Updated on2026-09-19
Q1.
From the figures below, what can you conclude about the magnitudes of a and b compared to each other, and what are their directions? Remember to start from 0. (1), (2), (3)
1.
2.
3.
The three pictures on page 27. In each one the coin starts at 0, the first strike is a and the second is b; the dashed coin shows where it lands in between and the solid coin its final position P.
Answer
In every figure, a is the first strike and b is the second, and P = a + b is where the coin finally stops. Read each arrow’s direction, then compare its length.
Figure 1
Figure 1: a takes the coin right of 0; the longer b brings it back past 0 to P.
a is positive (rightward) and b is negative (leftward), and the b-arrow is clearly the longer one.
magnitude of b > magnitude of a a is rightward (positive), b is leftward (negative) P = a + b is negative — P lies to the left of 0
Figure 2
Figure 2: the long a goes right; the shorter b comes back, but P stays right of 0.
a is positive (rightward) and b is negative (leftward), but this time the a-arrow is the longer one.
magnitude of a > magnitude of b a is rightward (positive), b is leftward (negative) P = a + b is positive — P lies to the right of 0
Figure 3
Figure 3: a carries the coin left, b brings it exactly back. P sits on 0.
a is negative (leftward) and b is positive (rightward), and the two arrows are the same length — P has landed back on 0.
magnitude of a = magnitude of b a is leftward (negative), b is rightward (positive) P = a + b = 0, so b = –a
Why it happens: the sign of P is decided by whichever movement has the greater magnitude, because the smaller one is completely cancelled by part of the bigger one. Only what is left over survives, and it keeps the direction of the bigger strike. When the magnitudes are equal, nothing is left over at all — the two movements are additive inverses and P = 0.
Tip: a picture like this never gives you exact numbers, only comparisons. Reading “b is longer than a and points the other way” is enough to say P is negative.