Question

This is a motion diagram of an object moving along the x-direction with constant
acceleration. The dots 1, 2, 3, ... show the position of the object at equal time
intervals ∆t .

__°5______°4___|__°3___°2_°1 x

x=0
At the time labeled 3, what are the signs of the object's velocity Vx and acceleration ax?
A. vx<0; ax>0
B. vx>0; ax<0
C. vx<0; ax<0
D. VX<0, ax=0​

Answer 1

Answer:

C

Explanation:

Because the object is moving with constant acceleration, we know that the object must also have an instantaneous velocity. Also, it doesnt say wether the object starts to slow down, in which case the acceleration would be in the direction opposite to the instantaneous velocity vector. As it doesnt say that, we can assume the object is still accelerating in position 3 and therefore the instantaneous velocity vector and the tangential acceleration vector will have the same direction (notice that i say tangential acceleration vector, because, as the trajectory is a straight line, the normal acceleration = 0). As the only option with both vectors having the same direction (sign) is C, the answer must be that one.

Answer 2

The dots 1, 2, 3. ... Show The Position Of The Object At Equal Time Intervals Delta T Which Of The Following A-1 Graphs Best ... An Object Moves Along The X-axis With Constant Acceleration. ... 0 m east of a signpost, moving east at 15m/s.