Question

A pencil and a pen roll horizontally off a desk at the same time. The pen has a higher velocity when they leave the desk. For each of the following quantities, tell whether the pen or pencil will have higher magnitude, or whether they will be the same and why.

1. Vertical displacement.

2. Total displacement.

3.Vertical acceleration.

4. Total acceleration.

5. Horizotal final velocity.

6. Total final veocity.

7. Time to hit the ground.

Answer 1

1) vertical displacement will be the same for both. (the height of the desk from ground is same for both)

2) total displacement will be more for pen because as the velocity of pen is higher when leaving the desk i.e the horizontal velocity is higher, the horizontal displacement will be higher for pen and the vertical displacement being same and hence the total displacement is more for pen.

3) vertical acceleration is the same equal to the acceleration due to gravity.

4) Total acceleration is also same as no other force other than gravity acts on them.

5) Horizontal final velocity will be more for pen as after leaving the desk the horizontal velocities won't be changed.

6) Total velocity is more for pen as the horizontal velocity is higher for pen.

7) Time to hit the ground is the same for both as the t = square root (2s / g).