Forces Test 1 Review

Academic Physics

Problem 1• A pencil (m = 0.01kg) is dropped from some height. Focus on

the point the pencil is released.– Calculate the weight of the pencil– Draw an FBD for the pencil– Is the situation representative of equilibrium or nonequilibrium?– What will happen to the motion of the pencil as it falls?

• Consider Velocity• Consider Forces• Consider Acceleration

Problem 2• A piece of paper (m = 0.001kg) is falling at its terminal

velocity towards the ground.– Calculate the weight of the paper– Draw an FBD for the paper– Is the situation representative of equilibrium or nonequilibrium?– What is the net force and acceleration on the paper?– What is the force of air resistance on the paper?

Problem 3• A hockey puck (m = 0.300kg) is being struck on an icy and flat

surface with a force of 20N from the hockey stick.– Calculate the weight of the puck– Draw an FBD for the puck– Is the situation representative of equilibrium or nonequilibrium?– What is the net force on the puck?– What is the acceleration of the puck?

Problem 4• A crate (m = 15kg) is being pushed across a floor ( = 0.03)

with a force of 20N applied.– Calculate the weight of the crate– Draw an FBD for the crate– Calculate the force of friction on the sliding crate– Is the situation representative of equilibrium or nonequilibrium?– What is the net force on the crate?– What is the acceleration of the crate?

Problem 5• A brick (m = 2kg) is sliding across a concrete floor ( = 0.6),

having been released and allowed to slide freely.– Calculate the weight of the brick– Draw an FBD for the brick– Calculate the force of friction on the sliding brick– Is the situation representative of equilibrium or nonequilibrium?– What is the net force on the brick?– What is the acceleration of the brick?

NOW FOR SOME SOLUTIONS!

Problem 1• A pencil (m = 0.01kg) is dropped from some height. Focus on

the point the pencil is released.– Calculate the weight of the pencil– Draw an FBD for the pencil: below– Is the situation representative of equilibrium or nonequilibrium?– What will happen to the motion of the pencil as it falls?

• Consider Velocity• Consider Forces• Consider Acceleration

Problem 2• A piece of paper (m = 0.001kg) is falling at its terminal

velocity towards the ground.– Calculate the weight of the paper– Draw an FBD for the paper: below– Is the situation representative of equilibrium or nonequilibrium?– What is the net force and acceleration on the paper?– What is the force of air resistance on the paper?

Problem 3• A hockey puck (m = 0.300kg) is being struck on an icy and flat

surface with a force of 20N from the hockey stick.– Calculate the weight of the puck– Draw an FBD for the puck: below (side view)– Is the situation representative of equilibrium or nonequilibrium?– What is the net force on the puck?– What is the acceleration of the puck?

Problem 4• A crate (m = 15kg) is being pushed across a floor ( = 0.03)

with a force of 20N applied.– Calculate the weight of the crate– Draw an FBD for the crate: below– Calculate the force of friction on the sliding crate– Is the situation representative of equilibrium or nonequilibrium?– What is the net force on the crate?– What is the acceleration of the crate?

Problem 5• A brick (m = 2kg) is sliding across a concrete floor ( = 0.6),

having been released to the right and allowed to slide freely.– Calculate the weight of the brick– Draw an FBD for the brick: below– Calculate the force of friction on the sliding brick– Is the situation representative of equilibrium or nonequilibrium?– What is the net force on the brick?– What is the acceleration of the brick?