Forces And motion Flashcards
What does it mean when an object is not moving?
It means the forces acting on it are balanced, not that no forces are acting on it.
What are the two forces acting on a rock sitting on the ground?
The force of gravity (pulling it down) and the contact force from the ground (pushing up).
Why doesn’t the rock move towards the center of the Earth?
Because the contact force from the ground balances the force of gravity.
What happens when the wind pushes against the rock?
The wind’s pushing force is balanced by friction between the rock and the ground, preventing movement.
How are forces represented in a force diagram?
With arrows that show the size and direction of each force; longer arrows represent stronger forces.
What do equal-length arrows pointing in opposite directions represent in a force diagram?
Balanced forces.
What happens when a rock is pushed with a force larger than friction?
The forces become unbalanced, and the rock will start to move.
In the context of a force diagram, what indicates that forces are unbalanced?
When one arrow is longer than the other, indicating a stronger force in one direction.
What happens to the rock when a large force, such as a vehicle, pushes it compared to just the wind?
When a large force pushes the rock, it overcomes the friction, resulting in unbalanced forces that cause the rock to move. When only wind pushes the rock, the force is balanced by friction, so the rock does not move.
How do unbalanced forces affect the movement of the rock?
Unbalanced forces cause the rock to move in the direction of the larger force, as the friction is no longer sufficient to balance it.
What effect do unbalanced forces have on a moving object?
Unbalanced or unequal forces can make a moving object slow down.
How does a parachute affect a falling object?
The parachute creates a force of air resistance that is larger than the weight of the object, slowing it down.
What happens to the forces acting on an object when a parachute first opens?
When the parachute first opens, air resistance is greater than the weight of the object, resulting in unbalanced forces that slow it down.
What occurs once the falling object slows down due to the parachute?
The air resistance decreases until it matches the weight of the object, and the forces become balanced.
What happens to the speed of the object when the forces acting on it become balanced again?
The object falls at a constant speed once the forces are balanced.
How can balanced and unbalanced forces be represented in a force diagram of a parachute?
When the forces are unbalanced, the arrow for air resistance is longer than the arrow for weight. When balanced, the arrows for air resistance and weight are equal.
How does a tennis ball change direction when hit by a racket?
When the ball contacts the racket, the hitting force must be larger than the force from the ball to make it change direction, resulting in an unbalanced force.
In a force diagram of a tennis ball hitting a racket, what do the arrows represent?
The arrows represent the hitting force on the ball and the force from the ball on the racket, indicating the interaction and change in direction.
In the diagram of a planet orbiting the Sun, what does the arrow pointing towards the Sun represent?
The arrow represents the force of gravity from the Sun, which constantly changes the direction of the planet’s movement, keeping it in orbit.
Why is the rope not moving when both Team A and Team B are pulling on it in a tug of war?
The rope is not moving because the forces exerted by both teams are equal in size but opposite in direction, resulting in balanced forces.
What two changes could make the rope move towards Team B in a tug of war?
Team B could either increase their pulling force or Team A could decrease their pulling force, resulting in unbalanced forces that make the rope move towards Team B.
Why is the aeroplane in the diagram flying at a constant speed and not getting higher or lower?
The forces acting on the aeroplane—thrust, drag, lift, and weight—are balanced. Thrust equals drag, maintaining constant speed, and lift equals weight, keeping it at the same altitude.
Which force should increase to make the aeroplane go faster?
The thrust should increase to make the aeroplane go faster.
Which force should increase to make the aeroplane go higher or gain lift?
The lift should increase to make the aeroplane go higher.
Which force should decrease to make the aeroplane go lower?
The lift should decrease to make the aeroplane go lower.
Which force should decrease to make the aeroplane go faster?
The drag should decrease to make the aeroplane go faster.
In the toy train moving around a circular track, what is the direction of the driving force of the train?
The driving force of the train is shown by the arrow labeled A.
Which arrow shows the force of friction on the locomotive of the toy train?
The force of friction is shown by the arrow labeled B.
Which arrow shows the force that keeps the toy train moving in a circle?
The force that keeps the toy train moving in a circle is shown by the arrow labeled C.
