In a differential drive system, if the left wheel moves backward and the right wheel moves forward, the robot will:

• A. The robot spins in place to the left.
• B. The robot spins in place to the right.
• C. The robot moves straight ahead.
• D. The robot turns to the left.

Answer: (C)

In a differential drive system, how the robot moves comes from the two wheel speeds. The forward speed of the chassis is the average of the left and right wheel speeds, while the turn rate (how quickly it rotates from side to side) depends on the difference between the two speeds.

If the left wheel moves backward and the right wheel moves forward, the wheel speeds have opposite signs. That creates a large difference between them, so the robot doesn’t translate straight ahead. Instead, it rotates about its center. If the magnitudes are equal, it spins in place (no forward movement); if the magnitudes differ, it turns along a circular path around a point between the wheels. So the motion is rotational, not straight-line propulsion.