Question

While riding in a moving car, you toss an egg directly upward. Does the egg tend to land behind you, in front of you, or back in your hands if the car is (a) traveling at a constant speed, (b) increasing in speed, and (c) decreasing in speed?

Short answer

1. Landing position of egg when car travelling at constant speed is back in our hands.
2. Landing position of egg when car travelling with increasing speed is behind us.
3. Landing position of egg when car travelling with decreasing speed is in front of us.

Step-by-step solution

Given information

While riding in a moving car, an egg has been tossed directly upward.

To understand the concept

It deals with the kinematic equations of motion in which the motion can be described with constant acceleration. Also, this problem is based on the concept of projectile motion. When a particle is thrown near the earth’s surface, it travels along a curved path under constant acceleration directed towards the center of the earth surface. Using this concept and kinematic equation, it can be found where egg will land.

Formulae:

The displacement in kinematic equation is given by,

$D=V_{0}t+\left(\frac{1}{2}\right)a{t}^2$

(a) To find the landing position of egg when car travelling at constant speed.

When car is travelling with constant speed, egg also have that speed. When egg is thrown upward it travels projectile path and returns at same level. In this case vertical velocity component of egg changes because of acceleration due to gravity is vertically downward acting. But there is no acceleration along horizontal direction so the egg will have same horizontal velocity throughout motion and egg will land back in our hands.

(b) To find the landing position of egg when car travelling with increasing speed is behind us.

When car is increasing speed, the horizontal velocity of egg will be the velocity of that moment when it was thrown. Once egg is thrown it will have constant velocity acquired before thrown. Here, car is increasing its speed so egg will land behind us.

(c) To find the landing position of egg when car travelling with decreasing speed is in front of us.

When car is decreasing speed, the horizontal velocity of egg will be the velocity of that moment when it was thrown. Once egg is thrown it will have constant velocity acquired before thrown. Here, car is decreasing its speed so egg will land in front of us