A rock is thrown upward at 51.1◦
with respect
to the horizontal. As it rises, its vertical
component of velocity
1. remains unchanged.
2. decreases.
3. increases.
4. Unable to determine.
since the only force acting on the rock is gravity pulling down, (b)
To answer this question, we need to understand the motion of the rock when it is thrown upward at an angle of 51.1° with respect to the horizontal.
When an object is launched at an angle, it can be divided into two components of motion: horizontal and vertical.
In this case, the horizontal component of velocity is not relevant to the vertical motion of the rock. Therefore, we can focus solely on the vertical component of velocity.
Now, when an object is thrown upward against the force of gravity, its vertical velocity will change due to the influence of gravity. In the absence of any external forces, such as air resistance, we can analyze the motion by considering the effects of gravity.
As the rock moves upward, gravity acts against its motion, reducing its upward velocity. At the highest point of its trajectory, known as the vertex, the object momentarily stops moving upward before beginning to descend. During the upward motion, the rock will experience a decrease in its vertical component of velocity.
Therefore, the correct answer to the question is option 2: The vertical component of velocity decreases as the rock rises.