Question

In projectile motion, power of the gravitational force
A. Is constant throughout
B. Is negative for first half, zero at topmost point and positive for rest half
C. Varies linearly with time
D. Is positive for complete path

Answer 1

A projectile is an item on which gravity is the sole force operating. Projectiles come in a range of shapes and sizes. A projectile is an item that is launched from its resting position (provided that the influence of air resistance is negligible). A projectile is an item that is hurled vertically upward (provided that the influence of air resistance is negligible)

Complete step by step solution:
A projectile is also an item that is hurled upward at an angle to the horizontal (provided that the influence of air resistance is negligible). A projectile is any item that, after being projected or dropped, continues to move due to its own inertia and is solely impacted by gravity's downward pull.
Gravity opposes the vertical component of the projectile's velocity as it is launched. Let's say a projectile is launched at an angle A to the horizontal with a starting velocity u, then we can analyse the impact of gravity after breaking the velocity into two perpendicular components. Only the vertical component will be affected by gravity. As a result, the vertical component of its velocity is u sin A, and the projectile will continue to move upward until the downward direction of gravitational force acting on it causes its upward velocity to reach zero. As a result, the projectile has no vertical component of velocity at its greatest point of motion, only a horizontal component.
Following that, the projectile begins to fall, propelled by gravity. As a result, its height falls till it touches the earth. So, the horizontal component of velocity pushes it ahead, the vertical component of velocity pushes it higher, but the gravitational force pulls it back to the earth. The gravitational force's power in projectile motion is negative for the first half, zero at the top, and positive for the second half, and it varies linearly with time.
As a result, options (B) and (C) are the right answers.

Note:
A projectile is an item on which gravity is the sole force operating. Gravity influences the projectile's vertical motion, resulting in vertical acceleration. The projectile's horizontal motion is caused by the tendency for any moving item to maintain a constant velocity. A projectile maintains a constant horizontal velocity due to the absence of horizontal forces. To maintain a projectile travelling horizontally, no horizontal forces are necessary. Gravity is the sole force acting on a projectile.