Question

1. which simple machine is a bar that pivots around a fulcrum? *
2. larger wheels on a robot usually mean:

○ faster speed, less torque
○ slower speed, more torque
○ no change in speed
○ robot cannot move

Explanation:

Question 10:

In robotics and mechanical systems, the relationship between wheel size (radius), speed, and torque is based on mechanical power principles. Power \( P = \tau \omega \) (torque \(\tau\) times angular velocity \(\omega\)). For a wheel, linear speed \( v = r\omega \) (radius \( r \), angular velocity \(\omega\)). Larger wheels (larger \( r \)) at the same torque would have a lower angular velocity \(\omega\) to maintain power, but linear speed \( v = r\omega \) increases. However, torque and speed have an inverse relationship in such systems—larger wheels (more leverage for movement) mean the motor can provide more speed but less torque (since torque is force times radius, and larger radius with same force would have more torque? Wait, correction: Actually, when using gears or wheel - motor systems, a larger wheel (higher gear ratio in terms of wheel size) will result in slower speed but more torque? No, wait, let's think of a bicycle. Larger wheels (like on a road bike vs a BMX) – wait, no, in robot wheels, if the wheel is larger, for the same motor rotation (angular displacement), the linear distance covered is more (so speed is faster), but the torque required: Torque \(\tau = rF\), where \( F \) is the force. If the wheel is larger (larger \( r \)), to get the same force \( F \) at the contact point, the motor needs to apply less torque (since \(\tau\) is proportional to \( r \) for a given \( F \)). Wait, no—actually, the motor's torque is what drives the wheel. The wheel's radius affects the mechanical advantage. A larger wheel (larger radius) will have a higher linear speed for the same motor angular velocity (since \( v = r\omega \)), but the torque available at the wheel for moving the robot (the torque that can overcome resistance) is less. Because torque and speed in a mechanical system with a fixed power source (the motor's power \( P=\tau_{motor}\omega_{motor}\)) are inversely related. When we increase the wheel size (effectively a gear ratio change), the speed (linear) increases, and the torque (the rotational force the wheel can exert to move the robot) decreases. So larger wheels mean faster speed, less torque.

A lever is a simple machine defined as a rigid bar that pivots around a fixed point called a fulcrum. It is used to multiply force or change the direction of a force. Other simple machines like pulleys (use ropes and wheels), inclined planes (flat sloped surfaces), screws (inclined planes wrapped around a cylinder), and wedges (triangular - shaped to split objects) do not fit the description of a bar pivoting around a fulcrum. So the simple machine that is a bar pivoting around a fulcrum is a lever. (Note: Since the options for question 1 are not provided in the image, but based on the question "Which simple machine is a bar that pivots around a fulcrum?", the answer is a lever. If there were options like A. Lever, B. Pulley, C. Inclined Plane, D. Screw, the correct option would be the one with "Lever".)

Answer:

Faster speed, less torque

Question 1: