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Q4.6: NCERT Physics - Part 1 LAWS OF MOTION 4.6 Solution: A constant force acting on a body of mass 3.0 kg changes its…

⚠️ Common Exam Traps & Conceptual Pitfalls

When computing acceleration from a change in speed, use $a= rac{v-u}{t}$; swapping the terms gives a negative sign and leads to an incorrect force direction. Always verify that the sign of $a$ matches the direction of motion before applying $F=ma$.

A constant force acting on a body of mass 3.0 kg changes its speed from 2.0 m s__ to 3.5 m s__ in 25 s. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force?

Step-by-Step Verified Solution

**Answer:** F = 0.18 N, in the direction of motion **Step-by-Step Explanation:** Acceleration:
a=v−ut=3.5−2.025=0.06 m/s2a = \frac{v - u}{t} = \frac{3.5 - 2.0}{25} = 0.06 \text{ m/s}^2
Force:
F=ma=3.0×0.06=0.18 NF = ma = 3.0 \times 0.06 = 0.18 \text{ N}
The force acts in the direction of motion since the speed increases [citation:10].

All Questions in this Chapter

Q4.1 Q4.2 Q4.3 Q4.4 Q4.5 Q4.6 Q4.7 Q4.8 Q4.9 Q4.10 Q4.11 Q4.12 Q4.13 Q4.14 Q4.15 Q4.16 Q4.17 Q4.18 Q4.19 Q4.20 Q4.21 Q4.22 Q4.23

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