1D kinematics

Question 1

Velocity of an object changes from -10.0 m/s to -2.0 m/s in 8 seconds. What are the signs of average velocity and average acceleration(A) of this object?

Answer 1

Vavg is negative, Aavg is positive

Question 2

Relation between the signs of velocity and accel?

Answer 2

Sign of velocity shows the direction of motion. Sign of acceleration shows how the velocity
changes.
-Object speeds up only if velocity and acceleration have the same signs (both positive or both negative)
-Object slows down if velocity and acceleration have opposite signs, one is negative and the other one is positive.

Question 3

what is equal to the slope of a velocity vs time graph?

Answer 3

Acceleration is equal to the
slope of velocity-time graph

Question 4

if a piece of paper and a heavy book are dropped simultaneously side by side, the paper slowly drifts down while the book accelerates at g. Do you think the outcome of this experiment will be different if your instructor drops the piece of paper and the book simultaneously with the paper sitting on top of the book?

Answer 4

Both objects will fall at the same rate.
As the objects drop, the book pushes the air down. Therefore, there is no air resistance on the paper and both drop at the same rate.

Question 5

You throw a ball straight upward at an initial velocity of +5.00 m/s. It reaches a maximum height y𝑚𝑎𝑥 before turning around and moving in downward direction. What are the velocitya nd the acceleration of the ball at ymax�

Answer 5

0, -9.81m/s^2

Question 6

Ball is thrown straight upwards with Vi=5.00 m/s before turning around and moving in downward direction, how long does it take the ball to reach the maximum height, ymax�

Answer 6

Velocity at the top is zero. Initial velocity is given and acceleration in free fall is known. So, you can use the kinematic equation vf=vi+at to find the time.

t=0.510s