Velocity problem did i do it right?

[BeckyStar678]

Homework Statement

a cart is pushed along a straight horizontal track
a.) in a certain section of its motion, its original velocity is +3 m/s and it undergoes a change in velocity of +4 m/s. does it speed up or slow down in this section of motion? is its acceleration positive or negative?

b.) in a certain section of its motion, its original velocity is -3 m/s and it undergoes a change in velocity of +4 m/s. does it speed up or slow down in this section of motion? is its acceleration positive or negative?

c.)in a certain section of its motion, its original velocity is +3 m/s and it undergoes a change in velocity of -4 m/s. does it speed up or slow down in this section of motion? is its acceleration positive or negative?

d.) in a certain section of its motion, its original velocity is -3 m/s and it undergoes a change in velocity of -4 m/s. does it speed up or slow down in this section of motion? is its acceleration positive or negative?

Homework Equations

The Attempt at a Solution

a.) it increases and acceleration is +
b.) it decreases and acceleration -
c.) it decreases and acceleration is -
d.) it increases and acceleration is +

 

[LowlyPion]

Homework Statement

a cart is pushed along a straight horizontal track
a.) in a certain section of its motion, its original velocity is +3 m/s and it undergoes a change in velocity of +4 m/s. does it speed up or slow down in this section of motion? is its acceleration positive or negative?

b.) in a certain section of its motion, its original velocity is -3 m/s and it undergoes a change in velocity of +4 m/s. does it speed up or slow down in this section of motion? is its acceleration positive or negative?

c.)in a certain section of its motion, its original velocity is +3 m/s and it undergoes a change in velocity of -4 m/s. does it speed up or slow down in this section of motion? is its acceleration positive or negative?

d.) in a certain section of its motion, its original velocity is -3 m/s and it undergoes a change in velocity of -4 m/s. does it speed up or slow down in this section of motion? is its acceleration positive or negative?

Homework Equations

The Attempt at a Solution

a.) it increases and acceleration is +
b.) it decreases and acceleration -
c.) it decreases and acceleration is -
d.) it increases and acceleration is +

Put the velocities out on a number line. Negative to positive, left to right.

Any change when you go from initial to final that is left to right is positive change. To the right is negative change.

Look at your problem again.

 

[BeckyStar678]

Put the velocities out on a number line. Negative to positive, left to right.

Any change when you go from initial to final that is left to right is positive change. To the right is negative change.

Look at your problem again.

okay, so by looking at it again i got
a.) it increases and acceleration is +
b.) it increases and acceleration -
c.) it decreases and acceleration is -
d.) it decreases and acceleration is +

i changed the accelerations because isn't it that when the signs are the same, that means that acceleration is + and when the signs are different the acc. is -?

 

[LowlyPion]

okay, so by looking at it again i got
a.) it increases and acceleration is +
b.) it increases and acceleration -
c.) it decreases and acceleration is -
d.) it decreases and acceleration is +

i changed the accelerations because isn't it that when the signs are the same, that means that acceleration is + and when the signs are different the acc. is -?

It's the direction of the change in velocities. If velocity decreases, then acceleration is in the "decreasing" direction - i.e."-" - whether or not the signs of velocity are positive or negative. It's whether the differences are + or -.

Like housing values are determined by Location. Location. Location.
Here it's Direction. Direction. Direction.