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Blazing goIITian

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16 Jun 2009 12:50:36 IST

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Some superb IIT level questions just for goiitians:___

General

The velocity of a particle moving along the x axis varies in
time according to the expression v(x)={40-5t^2} m/s, where
t is in seconds. (a) Find the average acceleration in the time
interval t = 0 to t = 2.0 s.

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eragon24

Blazing goIITian

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16 Jun 2009 12:51:18 IST

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where r the questions??????

STONE COLD RATTLESNAKE

Blazing goIITian

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16 Jun 2009 13:06:49 IST

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If a car is traveling eastward, can its acceleration be westward? (b) If a car is slowingdown, can its acceleration be positive?

STONE COLD RATTLESNAKE

Blazing goIITian

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16 Jun 2009 13:06:55 IST

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If a car is traveling eastward, can its acceleration be westward? (b) If a car is slowingdown, can its acceleration be positive?

STONE COLD RATTLESNAKE

Blazing goIITian

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16 Jun 2009 13:06:58 IST

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If a car is traveling eastward, can its acceleration be westward? (b) If a car is slowingdown, can its acceleration be positive?Consider the following one-dimensional motions: (a) A ballthrown directly upward rises to a highest point and falls backinto the thrower?s hand. (b) A race car starts from rest andspeeds up to 100 m/s. (c) A spacecraft drifts through space atconstant velocity. Are there any points in the motion of theseobjects at which the instantaneous velocity is the same as theaverage velocity over the entire motion? If so, identify thepoint(s).

NugoRama

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16 Jun 2009 13:52:58 IST

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Q. The velocity of a particle moving along the x axis varies in time according to the expression v(x)={40-5t^2} m/s, where
t is in seconds. (a) Find the average acceleration in the time interval t = 0 to t = 2.0 s.

A. Average acceleration is change in velocity / time

at t = 0, v = 40 , at t = 2, v = 20

avg accn = (20 - 40) / 2 = -10m/s^2

Q. (a) If a car is traveling eastward, can its acceleration be westward?

A. Yes...it can be ..this is called retarding motion .

(b) If a car is slowingdown, can its acceleration be positive?

A. Yes..Consider a stone thrown up ...when it is going up..its slowing down,and accn is downwards.

But if we take downward direction as positive...its still slowing down ..but accn is positive.

Note: slowing down = decreasing speed not decreasing velocity.

Q. Consider the following one-dimensional motions: (a) A ball thrown directly upward rises to a highest point and falls backinto the thrower's hand. (b) A race car starts from rest andspeeds up to 100 m/s. (c) A spacecraft drifts through space atconstant velocity. Are there any points in the motion of these objects at which the instantaneous velocity is the same as theaverage velocity over the entire motion? If so, identify thepoint(s).

A. For case (a) ..average velocity = 0, and at highest point inst. vel = 0 too.

For case (b) ...We dont know the Value of accn ..but we can surely say that the average velocity is b/w 0 and 100.

..And at Minimum one particular point ..the car must be having inst. vel = the avg vel( cos it takes all the values from 0 to 100)

For case (c) If the vel is maintained constant ..at evry point its having avg vel = inst. velocity.

The end.

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