Question

Difficulty: EasyKinematics and Linear Motion

A train accelerates uniformly along a straight track from an initial velocity of 10 m/s10\text{ m/s} to a final velocity of 30 m/s30\text{ m/s} over a distance of 100 m100\text{ m}. What is the magnitude of the acceleration of the train?

  1. A
    0.2 m/s20.2\text{ m/s}^2
  2. 4 m/s24\text{ m/s}^2Answer
  3. C
    5 m/s25\text{ m/s}^2
  4. D
    8 m/s28\text{ m/s}^2

Answer

4 m/s24\text{ m/s}^2
Using the equation of motion v2=u2+2asv^2 = u^2 + 2as, substitute u=10 m/su = 10\text{ m/s}, v=30 m/sv = 30\text{ m/s}, and s=100 ms = 100\text{ m}. This gives 302=102+2(a)(100)30^2 = 10^2 + 2(a)(100), which simplifies to 900100=200a900 - 100 = 200a, or 800=200a800 = 200a. Solving for acceleration yields a=4 m/s2a = 4\text{ m/s}^2.

Step-by-Step Solution

1
Identify the given kinematic values from the problem statement.
Initial velocity u=10 m/su = 10\text{ m/s}, final velocity v=30 m/sv = 30\text{ m/s}, and displacement s=100 ms = 100\text{ m}.
Listing known values helps in selecting the appropriate equation of motion.
2
Select the linear motion formula relating uu, vv, ss, and acceleration aa.
v2=u2+2asv^2 = u^2 + 2as
This formula connects initial velocity, final velocity, distance, and acceleration without requiring time tt.
3
Substitute the values into the equation and solve for aa.
302=102+2(a)(100)    900=100+200a    800=200a    a=4 m/s230^2 = 10^2 + 2(a)(100) \implies 900 = 100 + 200a \implies 800 = 200a \implies a = 4\text{ m/s}^2
Algebraic rearrangement yields the magnitude of acceleration.

Key Concept

Equations of Uniformly Accelerated Motion
Estimated Time:45s
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