Canada Grade 6 Science Flight: Basic principles

What is the force that allows airplanes to rise into the air?

• Thrust

• Drag

• Lift

• Weight

Answer explanation

Lift is the upward force generated by the wings of an airplane as air flows over and under them. This force counteracts weight and allows the airplane to rise into the air.

Which force opposes the forward motion of an airplane?

• Thrust

• Drag

• Lift

• Weight

Answer explanation

Drag is the aerodynamic force that opposes the forward motion of an airplane. It acts in the opposite direction to thrust, slowing the aircraft down. Thrust propels the plane forward, while lift and weight act vertically.

What is thrust?

• The force pulling an airplane downward

• The force pushing an airplane forward

• The force lifting an airplane upward

• The resistance slowing an airplane down

Answer explanation

Thrust is the force that propels an airplane forward, generated by the engines. It is essential for overcoming drag and achieving flight, making 'the force pushing an airplane forward' the correct definition of thrust.

How do birds create lift when they fly?

• By flapping their wings rapidly

• By spreading their tail feathers

• By curving their wings and flapping

• By flying against the wind

Answer explanation

Birds create lift by curving their wings and flapping. This shape allows air to move faster over the top of the wing, reducing pressure and generating lift, which is essential for flight.

What part of an airplane helps control its lift?

• The rudder

• The fuselage

• The wings

• The engine

Answer explanation

The wings are crucial for generating lift in an airplane. They are designed to create a difference in air pressure above and below them, allowing the aircraft to rise and stay in the air.

Which of the following best describes drag?

• A force that slows down a flying object

• A force that speeds up a flying object

• A force that pulls a flying object down

• A force that makes a flying object turn

Answer explanation

Drag is a force that opposes the motion of a flying object, causing it to slow down. Therefore, the best description of drag is 'A force that slows down a flying object.'

What force is created by an airplane's engines?

• Drag

• Lift

• Thrust

• Weight

Answer explanation

The force created by an airplane's engines is called thrust. Thrust propels the airplane forward, counteracting drag and allowing it to achieve lift. Lift is generated by the wings, while weight is the force of gravity.

Which bird is known for its long-distance gliding using air currents?

• Hummingbird

• Eagle

• Penguin

• Chicken

Answer explanation

The eagle is renowned for its ability to glide long distances using thermal air currents, allowing it to conserve energy while soaring high. In contrast, hummingbirds, penguins, and chickens do not possess this long-distance gliding capability.

What happens if lift is greater than weight?

• The object slows down

• The object flies upward

• The object falls to the ground

• The object stays in place

Answer explanation

When lift exceeds weight, the net force is upward, causing the object to accelerate upwards. Therefore, if lift is greater than weight, the object flies upward.

How does the shape of a wing help create lift?

• It makes air move faster above the wing

• It traps air below the wing

• It increases thrust

• It reduces drag

Answer explanation

The shape of a wing, specifically an airfoil, causes air to move faster over the top surface than the bottom. According to Bernoulli's principle, this difference in speed creates lower pressure above the wing, generating lift.