If a block moves left at constant velocity, Newton's First Law tells us the net force on it must be zero. This means no acceleration occurs—it's staying steady in speed and direction.

Core Conclusion

The key takeaway is straightforward physics: constant velocity implies balanced forces. No net force accelerates the block; any forces present (like friction opposing motion) cancel out exactly.

Imagine sliding a puck on ice—it glides left smoothly until friction slows it. Here, if velocity holds steady leftward, something (friction, air resistance) balances any push, netting zero force.

Multiple-Choice Breakdown

This question often appears in textbooks as a test of Newton's laws. Here's the typical setup and why only one option fits:

Option| Statement| Correct?| Reason
---|---|---|---
a| Exactly one force applied| No| Multiple forces can balance (e.g., push left, friction right). 3
b| Net force directed left| No| That would accelerate it left, speeding up—not constant velocity. 3
c| Net force is zero| Yes| Matches Newton's First Law perfectly. 15
d| No forces at all| No| Forces can exist if they sum to zero. 3

Real-World Examples

  • Pushing a crate : Apply 10N left; friction gives 10N right. Constant velocity left.
  • Spacecraft coasting : No engines, no drag—constant velocity forever (ideal vacuum).
  • Car at cruise control : Engine force balances drag/rolling resistance.

Common Misconceptions

Students mix this up with "no forces" (wrong—forces balance) or assume constant speed needs constant force (nope, only for acceleration).

From physics forums , many clarify: Direction (left) doesn't matter; it's the net zero that counts.

TL;DR : Net force is zero—option c. Forces balance for steady motion.

Information gathered from public forums or data available on the internet and portrayed here.