Robotics Semester 2 Final
A 10-tooth driver gear meshes with a 20-tooth idler gear, which in turn, meshes with a 40-tooth driven gear. What is the gear ratio of the gear train?
1 to 4
What amount of force is necessary to move a robot that weighs 4 lbs. at an acceleration of 12 ft/s2?
1.5 lbs.
Use the velocity-time graph to determine the acceleration of the object.
1.50 ft/s2
What is the wheel rollout of a 6 inch wheel in feet?
1.57 feet
A force of 25 lbs acting on a 6 in. wrench yields a torque of:
12.5 ft·lbs.
Given that the speed of sound is 1,000 feet/sec and that an echo takes 250 ms from the ping to the reception, what is the distance to the object being detected?
125 feet
If the environmental conditions are such that the speed of sound is 1,000 km/sec and that an echo takes 250 ms from the ping to the reception, what is the distance to the object being detected
125 meters
A robot has wheels with a 2.75 inch radius spinning at 100 RPM. How fast can it go?
14.4 in/s
A torque of 99 ounce·inches acting on a 6 in. wheel produces a force of:
2.1 lbs
If the BaseBot travels 15 ft. in 6.7 seconds, what is the average speed?
2.2 ft/s
In order for the Basebot to roll up a 10° slope it must exert a force that is at the very least equal the forces that work against it. If the forces acting downhill total 2.5 lbs, how much power is produced if the robot travels uphill at 1 ft/s?
2.50 lbs-ft/s
A robot has wheels with a 3 inch radius spinning at 100 RPM. How fast can it go?
2.6 ft/s
A 5 lb force acting on a 5 inch wheel will produce a torque of:
200 oz·in
A 12 tooth gear is driven by a 36 tooth gear attached to a motor that produces 90 oz·in of torque. How much torque will be provided to the wheels?
30 oz·in
How much does robot weigh if its mass is 0.125 slug?
4 lbs.
The motors on the robot act with a 5 lb. force to move the robot and friction acts with 1 lb. force. What is the net force acting on the robot?
4 lbs.
A 2.0 kg robot will weigh how many pounds?
4.4 lbs.
A 60 tooth gear is driven by a 12 tooth gear attached to a motor that produces 80 oz·in of torque. How much torque will be provided to the wheels?
400 oz·in
Find the work done when a block is moved a distance of 3 ft. by a force of 15 lbs.
45 lb-ft
Rubber on floor tile has a coefficient of kinetic friction of 1.0 and a coefficient of static friction of 2.0. How much force would a 3.5 lb. robot need to produce in order to start moving?
7.0 lbs.
A 5 inch wheel rolls 5 revolutions on a horizontal surface without slipping. How far did the wheel travel?
78.5 inches
The BaseBot starts at rest and accelerates to a speed of 1.6 ft/s in 2.3 seconds. What was the acceleration of the BaseBot?
8.3 in/s^2
The VEX Ultrasonic Sensor is connected to:
A digital output and an interrupt port.
Suppose you found that the line-following sensor returned a value of 36 for off the line and 457 for on the line. What might be a good threshold value to use for your program?
A value midway between 36 and 457.
The line-following sensor is designed to operate:
About 1/8" to 1/4" above the line, parallel to the floor.
The bumper switches and limit switches can be:
All answers are correct.
_________ is an example of an analog sensor.
An ultrasonic rangefinder
How can you increase the torque supplied by the Vex motors?
Change the gear ratio
What is the difference between an open-loop system and a closed-loop system?
Closed-loop systems include feedback to the system's program; open-loop systems do not include feedback.
What does the following symbol represent on the VEX controller configuration dialog? rec04_digital_in
Digital Input.
Which of the following is NOT an example of a sensor?
Door Opener
Sensors provide ______ to a program via the controller.
Feedback
Work is done when an object is moved a certain distance by which of the following?
Force
The values passed to the function TwoWheelDrive(); represent:
Motor Ports
Cars and robots are not limited by the amount of energy they use, but by the rate at which they use the energy. This is an example of limitation by what?
Power
When using gear trains in a robot, trade-offs must be made. If the robot needs to increase torque, there will be a proportional trade-off in what?
Speed
Why is it more difficult for a robot to start moving than it is to keep moving after it is in motion?
The coefficient of static friction is greater than the coefficient of kinetic friction.
The Mars Rover needed to have autonomous driving functions because:
The distance to Mars was so great that real-time remote control was impossible.
Which of these is NOT true of the Ultrasonic Sensor:
The sensor will return multiple distances when there are multiple targets.
Which factor does NOT affect the speed of sound?
The sound amplitude (loudness) and frequency.
Which of the following issues with driving the robot is not corrected by the new Drive Library?
There is limited resolution because there are only 127 possible motor values in each direction.
Mechanical switches provide a reliable method of determining the position of a robot. What is a reason to use an ultrasonic sensor in place of a switch?
To measure the distances to objects that are difficult to contact for measurement.
Which of the following statements is true of the line-following sensor?
Uses an LED and a photo detector to see the line.
Which sensor detects the amount of rotation?
Wheel encoder.
Select the statement that is False.
When you modify an imported library in easyC, the original library is also modified.
Sensors provide information to the robot concerning:
all of the above
The digital sensors contained within the VEX kit are two _________ and two ________.
bumper switches, limit switches.
When should a sensor be sampled?
c. Immediately before the program needs to make a decision. Correct
Digital sensors _______________.
can be only ON or OFF
Velocity can be defined as:
displacement traveled divided by the time it took.
Newton's 2nd Law says:
force equals the product of the mass and acceleration
Torque is:
force times moment arm length
Accelerations are produced by:
forces
The motors used in the VEX robotics kit are:
hobby servos
An autonomous robot ____________.
is controlled by an internal program and uses sensors to provide feedback
Which of the following is a rechargeable wet cell battery?
lead-acid
Which of the following is not a dry cell battery?
lead-acid
In the real-world example discussed in this unit, the garage door opener utilized a ________ to tell the controller when to cut power to the motor.
limit switch
Which of the following is NOT a unit of measure for angular velocity:
m/s
An electric motor is useful because it turns electricity into:
mechanical energy.
Which of the following is a gear head motor?
modified hobby servo
Friction is a force that always acts____.
opposed to the object's motion
Which parameter is important when two different diameter gears need to mesh properly?
pitch
The Basebot is propelled forward when the wheels:
roll
Torque acting on an object produces:
rotation
The part of the motor that turns is typically called the:
rotor Correct
All robots have the capabilities identified below. Which one must the robot perform first?
sensing
Which type of gears does the Vex robotics kit contain?
spur
The kinetic friction of one object sliding along a surface depends LEAST upon:
the area of contact
On a gear, the fulcrum is:
the center of the gear
Which of the following formulas will NOT determine the gear ratio of a gear train?
the pitch in the driven gear divided by the pitch in the driver gear.
Acceleration is defined as the change in:
velocity divided by the time it took.
The strength of a battery's charge is measured in:
volts
A motor works because of thousands of wire loops called:
windings
