Motion Q (am i dumb? i don't get it) (1 Viewer)

[A Leaf]

Hi there, I don't seem to understand how to approach this Trial question - the answer says B btw
If anyone can think of an explanation that'd be super helpful

 

[HeroWise]

Sure, The velocity shows direction So -ve means to the left That leaves us with B and D

we dont care about the sign in the acceleration we only care about its magnitude. So its increasing as acceleration is more than 0

therefore B

 

[fan96]

Conventionally, the right is taken as the positive direction (like on the Cartesian plane), a negative velocity means the particle is moving left.

Acceleration is the change in velocity. Since it is negative, the velocity is decreasing over time, i.e. moving further in the negative direction.

Now a constant velocity means the particle moves the same distance each second.
So if the velocity itself is changing then the distance is changing even more.

In this case the particle starts moving at .

Acceleration is given by , i.e. each second the velocity is changed by .

So the velocity of the particle after each second passes would be -3, -5, -7, -9...

Speed is the velocity, ignoring the sign. When we talk about speed we only care how fast the object is going, not which direction it's going.

So the speed of the particle after each second passes would be 3, 5, 7, 9... which is clearly increasing over time.

So the particle is moving to the left with increasing speed.

 

[fan96]

So its increasing as acceleration is more than 0

Actually in this case, since the initial velocity is negative, a positive acceleration means that the particle would be doing a U-turn, as the velocity goes from negative to zero (and eventually to positive). The magnitude of velocity (speed) would therefore be decreasing.

 

[HeroWise]

in a sense yeas but again we dont know its initial velocity

 

[A Leaf]

OOH, ok - thanks guys I get it now