1.If we know that velocity of a body is zero, when(in which cases) can we conclude that its acceleration is zero and when not.
Why?
2. If we hold an umbrella at an angle to protect against rain why do we hold it vertically in case of sunlight?

Question

1.If we know that velocity of a body is zero, when(in which cases) can we conclude that its acceleration is zero and when not.
Why?
2. If we hold an umbrella at an angle to protect against rain why do we hold it vertically in case of sunlight?

unklerhaukus · Answer

i dont really understand these questions

anonymous · Answer

well?

anonymous · Answer

what dont u understand?

unklerhaukus · Answer

zero velocity / acceleration relative to what reference frame exactly/

anonymous · Answer

a stationary frame, i guess

unklerhaukus · Answer

well in that case it is zero

anonymous · Answer

eg when a car is decelerating constantly, doesnt its velocity become zero and then negative

unklerhaukus · Answer

when the car is breaking it is decelerating, if it stops its velocity is zero, if it begins to move backwards it has negative acceleration

anonymous · Answer

Consider a mass-spring system in simple harmonic motion. When the displacement is maximum, the velocity is zero, and the acceleration is maximum. In a zero velocity case, the acceleration will also be zero if the net force is zero. Why? Because of Newton's Second Law.

I don't like the second question. I don't know what they are after here. If it were 5 o'clock in the afternoon, the sun is low, and you should probably hold the umbrella at an angle as to maximize the sun blocking affect of the umbrella

anonymous · Answer

can us plz give some other eg as i dont know anything much about simple harmonic motion yet

anonymous · Answer

well i think im being stupid
ace is rate of change in velocity doesbt matter if velocity is 0 right?

unklerhaukus · Answer

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