Physics · Forces and Motion
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A train travels on a straight track passing signal A at 20 m/s. It accelerates uniformly at 2 m/s^2 and reaches signal B 100m further than A. At B the velocity of the train in m/s is
- A
10
- B
20
- C
28
- D
56
Using the equation of motion:
v² = u² + 2as
where:
v = final velocity (at signal B)
u = initial velocity (at signal A) = 20 m/s
a = acceleration = 2 m/s²
s = distance between signals A and B = 100 m
Substituting the values, we get:
v² = (20)² + 2(2)(100)
v² = 400 + 400
v² = 800
v = √800
v ≈ 28.28 m/s
Rounding to the nearest whole number, the velocity at signal B is approximately 28 m/s
Much too slow, incorrect calculation
Initial velocity, not final velocity
Using the equation of motion:
v² = u² + 2as
where:
v = final velocity (at signal B)
u = initial velocity (at signal A) = 20 m/s
a = acceleration = 2 m/s²
s = distance between signals A and B = 100 m
Substituting the values, we get:
v² = (20)² + 2(2)(100)
v² = 400 + 400
v² = 800
v = √800
v ≈ 28.28 m/s
Rounding to the nearest whole number, the velocity at signal B is approximately 28 m/s
Much too fast, incorrect calculation
Tagged under Physics · Forces and Motion · 2023