- An oar is held in an oarlock, which acts as a fulcrum. A paddle is not captive, and can be moved freely.
- One rows with an oar, and paddles with a paddle.
- One faces backward to row, and forward to paddle.
- Oars are longer than paddles.
- Oars can be held with one or two hands. Paddles are held with two hands.
- Oars are used in pairs, and only have a blade at one end. Small craft can be propelled by a single paddle, and paddles may have blades at both ends.
Entries in transportation (12)
A car’s transmission converts the rotational energy generated by the engine to an appropriate speed and torque, and transmits this energy to the driven wheels. In a vehicle with a manual transmission, the engine is coupled to the transmission with a clutch, and a lever is used to select different gear ratios. In an automatic transmission car, a fluid coupling called a torque converter connects the engine to the transmission. An intricate system of planetary gears, clutches, bands, and hydraulics automatically changes gear ratios based on factors including engine speed, vehicle speed, and load.
- Smoothly changing gears at the correct time on a manual transmission car takes practice and skill. An automatic transmission handles gear changes without the driver’s intervention.
- Manual transmission cars require the driver to make more decisions and movements, operating three pedals with both feet, and often taking one hand off the steering wheel to change gears. Automatics are substantially easier to operate.
- Because the driver selects the gear ratio, manual transmissions offer a greater degree of control, which can be useful for aggressive maneuvers, or when driving on slippery surfaces.
- Manual transmission cars have a clutch pedal, which automatic vehicles lack.
- Manuals have a gear lever that is moved up, down, left, and right to select gears. Automatics have a gear selector mounted on the steering column or the floor that can only be moved up or down.
- Manuals can be parked by placing the transmission in first gear (or reverse) and/or by engaging the hand brake (also called the parking brake). Automatics can be parked by selecting the ‘Park’ position on the gear selector, and/or by engaging the parking brake.
- Automatic transmissions can shift between gears much faster than a human can execute a manual gear change, during which time the engine is not delivering power to the wheels.
- Manual transmissions have fewer moving parts, and are cheaper to purchase, maintain, and repair.
- The clutch on a manual transmission rigidly links the engine to the transmission when completely engaged; an automatic transmission’s torque converter can slip somewhat.
- Manual transmissions can offer slightly better fuel economy than automatic transmissions.
- Manual transmissions weigh less than automatic transmissions.
- Manual transmissions typically have five or six gear ratios; automatic transmissions are commonly produced with four or five speeds.
- When the driver steps off the throttle in a manual transmission car, it slows down. This is not the case with an automatic transmission. Consequently, the brakes are used more and wear more quickly on automatic transmission cars.
- It’s easier for an inexperienced driver to damage the engine or transmission in cars with manual transmissions.
- Automatics require active cooling; manuals don’t.
- A vehicle with a manual transmission and a dead starter can be push started; automatic transmission vehicles can’t.
A highway is a main public road.
An expressway is a limited-access divided highway designed for high-speed traffic, with few at-grade intersections and traffic lights.
Freeways are engineered for higher speeds than expressways. Freeways usually lack intersections, traffic lights, and stop signs. Access is only provided at grade-separated interchanges. In some regions, the terms freeway and expressway are used interchangeably. The free in freeway implies freedom from traffic, but may also be used to mean ‘at no cost’, in which case a freeway is a toll-free highway.
A turnpike is a highway on which tolls are collected.
A canoe is a small, light, open boat that tapers to a point at both ends.
A kayak is a small, narrow boat of Eskimo design with a watertight deck with one or more openings that enclose the occupants at the waist. Kayaks are sometimes considered to be a type of canoe.
- Kayaks have a covered deck; canoes do not.
- Canoes use a single-bladed paddle; kayaks use a double-bladed paddle.
- In a canoe, the paddler either sits on a seat or kneels. In a kayak, the paddler sits within the cockpit with his legs extended forward.
- Canoes are usually wider and flatter than kayaks.
- Kayaks are generally faster, while canoes tend to be more stable.
- Kayaks sit lower in the water than canoes.
Proper wheel alignment reduces tire wear, improves performance, and ensures that a vehicle travels in a straight line. The three primary angles adjusted during alignment are toe, camber, and caster. Recommended settings are typically a fraction of a degree for toe and camber, and less than 5 degrees for caster.
Toe is the angle of the left and right wheels relative to facing straight ahead, as viewed from above the car. The wheels are said to have toe-in when their leading edges point slightly toward one another. This enhances straight line stability in street cars. Toe-out occurs when the leading edges point away from each other, creating more responsive steering in race cars.
Camber is the angle of the wheels relative to vertical, as viewed from the front of the car. Camber is positive when the wheels tilt out at the top and negative when they tilt in at the top. Maximum cornering force is developed when the wheels are given a small negative camber. Excessive camber creates uneven wear on the inside or outside of the tire. Unequal camber causes the vehicle to pull to one side.
Caster is the angle of the steering axis relative to vertical, as viewed from the side of the car. The steering axis is the line around which the wheels pivot when you turn the steering wheel. When a line drawn through the steering axis intersects the ground ahead of the wheel’s contact patch, it has a positive caster angle. Like a shopping cart caster, positive caster tends to pull the wheels in line when traveling forward, improving straight line stability. If the steering axis intersects the ground behind the contact patch, the wheel has a negative caster angle, and will be more difficult to drive in a straight line. High caster angles increase steering effort.