Question

question 1
the speed of a car will increase if the cars
initial velocity is positive and its acceleration is negative.
initial velocity is positive and its acceleration is positive.
initial velocity is negative and its acceleration is positive.
initial velocity is positive and its acceleration is zero.
question 2
the graph above describes the motion of a ball. at what point does the ball have an instantaneous velocity of zero?
a
d
b
c

Explanation:

Step1: Recall velocity - acceleration relationship

Velocity increases when acceleration has the same sign as the initial velocity. Positive acceleration and positive initial velocity mean speeding up.

Step2: Analyze each option

• Option 1: Positive initial velocity and negative acceleration means slowing down.
• Option 2: Positive initial velocity and positive acceleration means speeding up.
• Option 3: Negative initial velocity and positive acceleration means slowing down first and then speeding up in the positive direction, but initially speed is decreasing.
• Option 4: Positive initial velocity and zero acceleration means constant velocity.

Step3: Analyze the velocity - time graph for Question 2

The instantaneous velocity is zero when the graph crosses the time - axis (where the velocity value is zero). In the given graph, this occurs at point C.

Answer:

Question 1: initial velocity is positive and its acceleration is positive.
Question 2: C