Yes, force is absolutely necessary to change the speed or direction of a body. This is a fundamental principle of physics known as Newton's First Law of Motion, also known as the Law of Inertia.

Here's why:

* Inertia: Every object in motion wants to stay in motion, and every object at rest wants to stay at rest. This tendency to resist changes in motion is called inertia.

* Force as the Cause: To overcome inertia and change the speed or direction of an object, you need to apply an external force. The force acts to accelerate the object, meaning it changes its velocity.

* The Larger the Mass, the More Force: The amount of force needed to change the motion of an object is proportional to its mass. A larger mass requires a larger force to achieve the same change in speed or direction.

Examples:

* Pushing a Cart: You need to push a shopping cart to get it moving (change its speed from zero to something).

* Turning a Car: You need to turn the steering wheel (applying a force) to change the car's direction.

* Stopping a Ball: You need to catch a ball (applying a force) to stop it from moving.

Summary: Force is the agent of change in motion. Without a force, an object will continue moving at a constant speed in a straight line, or remain at rest.