Balancing Forces

Directions We are going to explore the idea of Balance Forces by playing with this apple and asking a few questions about what we observe! When you see the white arrow, click on the apple to continue, otherwise, click on an answer choice.

Question 1 An apple is thrown directly into the air. What force(s) are acting on the apple during it’s flight? A)The force of GravityThe force of Gravity A)The force of your handThe force of your hand C) The Force of your hand and GravityThe Force of your hand and Gravity D) There are no forces acting on the appleThere are no forces acting on the apple

Correct! Once the apple has left my hand, I can’t apply any more force to it. This is because I can only use Contact Forces. Gravity, on the other hand, is a Field Force, and acts on the apple at all times.

Question 2 An apple is thrown into the air. Ignoring air resistance, the forces acting on it are….. A)BalancedBalanced A)Unbalanced, with the net force acting downwardsUnbalanced, with the net force acting downwards C) Unbalanced, with the net force acting upwardsUnbalanced, with the net force acting upwards D) There are no forces acting on the appleThere are no forces acting on the apple

Correct! Ignoring the air resistance, the only force acting on the apple is Gravity. Since gravity always pulls towards the center of the earth, the overall force (or Net Force) is just gravity: which will point downwards.

Question 3 An apple is resting in my hand. I can observe that it is not changing speed or direction. Because of this, I know… A)The apple has no massThe apple has no mass A)The apple has no accelerationThe apple has no acceleration C) The apple has no weightThe apple has no weight D) There are no forces acting on the appleThere are no forces acting on the apple

Correct! We already concluded that Gravity is always acting on the apple, so we know that there are forces acting on it. If we know that the speed and direction of the apple are not changing, then it cannot have any Acceleration.

Question 4 An apple is resting in my hand. Since I know it is experiencing no acceleration, and gravity acts on all objects, then… A) The apple is experiencing unbalanced forcesThe apple is experiencing unbalanced forces B) The net force is acting downwardThe net force is acting downward C) The apple is experiencing balanced forcesThe apple is experiencing balanced forces D) There are no forces acting on the appleThere are no forces acting on the apple

Correct! We know that to cause an acceleration, we need to use a force on the apple. If gravity is a force, and it is acting on the apple, than it should be moving. Since the apple is not moving, there must be another force which is “canceling” or Balancing the force of Gravity.

Question 5 Since the apple has no acceleration, I know there must be a force balancing the pull of gravity on the apple. What is causing this force? A)The molecules in the airThe molecules in the air A)The appleThe apple C) GravityGravity D) My handMy hand

Correct! We know that a force must be Balancing the pull of Gravity. If I move my hand, than the apple would fall: the balancing force disappears. If that is the case, than my hand must be what is providing an upward force to cancel the downward pull of Gravity.

Question 6 An apple is resting in my hand. I know this is because my hand is balancing the force due to gravity. Is my hand special? A)Yes, it is the only thing that can resist forcesYes, it is the only thing that can resist forces A)No, any solid object will oppose forces acting on itNo, any solid object will oppose forces acting on it C) No, all hands can hold applesNo, all hands can hold apples D) Yes, because you are Bill Nye the Science GuyYes, because you are Bill Nye the Science Guy

Correct! All solid objects resist forces upon them by applying an opposing force in the opposite direction. This is called a Normal force. All objects will resist with Normal forces to balance the outside force until they cannot resist any longer, at which point it breaks.

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