Intro Robotics 1st 3wk review 8/30/24

What is a gear ratio?

• The size of a gear

• The relationship between the rates at which two gears rotate

• The speed of a machine

• The amount of force applied to a gear

Answer explanation

A gear ratio defines how the speeds of two interlocking gears relate to each other. It indicates how many times one gear turns compared to the other, making it crucial for understanding mechanical advantage and speed in machines.

How does a higher gear ratio affect torque?

• Increases torque

• Decreases torque

• Has no effect on torque

• Reverses torque

Answer explanation

A higher gear ratio increases torque because it allows the engine to produce more rotational force at the wheels. This means that for the same engine power, the vehicle can move more effectively, enhancing acceleration.

Which of the following best describes mechanical advantage?

• The speed at which a machine operates

• The increase in force or torque achieved by using a machine

• The ratio between the sizes of gears

• The twisting force that causes rotation

Answer explanation

Mechanical advantage refers to the increase in force or torque that a machine provides, allowing a smaller input force to achieve a greater output force, making it easier to perform work.

What happens to speed when you use a lower gear ratio?

• Speed increases

• Speed decreases

• Speed remains the same

• Speed doubles

Answer explanation

Using a lower gear ratio increases torque but decreases speed. This is because lower gears are designed for power and acceleration rather than high speed, making 'Speed decreases' the correct choice.

Torque is best described as:

• The rate at which something moves

• A twisting force that causes rotation

• The ratio of the force produced by a machine

• The speed at which gears turn

Answer explanation

Torque is defined as a twisting force that causes rotation, making 'A twisting force that causes rotation' the correct choice. The other options describe different concepts unrelated to torque.

Which of the following scenarios involves high torque and low speed?

• Driving a car on a highway

• Riding a bicycle on a flat road

• Climbing a hill on a bicycle

• Spinning a top

Answer explanation

Climbing a hill on a bicycle requires high torque to overcome gravity, resulting in low speed. In contrast, driving on a highway and riding on flat roads involve higher speeds with less torque, while spinning a top is a high-speed, low-torque scenario.

What is the primary benefit of using a mechanical advantage?

• It makes tasks harder to accomplish

• It reduces the amount of force needed to perform a task

• It increases the speed of a machine

• It decreases the size of a machine

Answer explanation

The primary benefit of using a mechanical advantage is that it reduces the amount of force needed to perform a task, making it easier to lift or move heavy objects.

In a gear system, if Gear A has 10 teeth and Gear B has 20 teeth, what is the gear ratio?

• 1:1

• 1:2

• 2:1

• 1:10

Answer explanation

The gear ratio is calculated by dividing the number of teeth on Gear B by the number of teeth on Gear A. Here, it is 20 teeth (Gear B) ÷ 10 teeth (Gear A) = 2. Thus, the gear ratio is 1:2.

If Gear A (input) rotates faster than Gear B (output), what can be said about the torque of Gear B?

• Torque is lower on Gear B

• Torque is higher on Gear B

• Torque is the same on both gears

• Torque is irrelevant in this situation

Answer explanation

When Gear A rotates faster than Gear B, it implies that Gear B experiences a greater torque to maintain the output speed. Therefore, the torque is higher on Gear B.

When would you want to use a low gear ratio in a car?

• When driving on a flat highway

• When accelerating quickly

• When climbing a steep hill

• When driving downhill

Answer explanation

A low gear ratio provides more torque, which is essential for climbing steep hills. It allows the engine to deliver power more effectively, helping the vehicle to ascend without stalling.