Forces and Patterns of Motion

A boy and his dog are pulling on each end of a rope. The boy is pulling with more force than the dog. How will the rope respond to unbalanced forces pulling in opposite directions?

• It will not move.

• It will move downward.

• It will move toward the boy.

• It will move toward the dog.

Tags

NGSS.MS-PS2-2

Ari sets up an investigation with a cart, four masses (used to cause a pulling force on the cart), a pulley, and a stopwatch on a smooth metal table. He adds one mass to the string attached to the back of the cart. He lets go of the cart and uses a stopwatch to see how long it takes the cart to travel to the end of the table. He adds one more mass to the cart and repeats his procedure. He does this until all of the masses have been used. He compares the data to see what mass caused the cart to move the fastest.

• What is the effect of friction on the cart?

• What is the result if the cart is subjected to balanced forces?

• How does changing the force on the cart affect the motion of the cart?

• How does the change in motion of the cart affect the mass on the cart?

Tags

NGSS.MS-PS2-2

Amara asks the question: How much force will it take to break a spaghetti noodle? She sets up an investigation where she rests a spaghetti noodle between two chairs and ties a paper cup to the noodle with a string. Amara measures and records the mass of a nickel. Then she adds nickels one at a time to the paper cup until the spaghetti noodle breaks. How can Amara describe the forces in her investigation?

• The chairs are exerting force on the paper cup.

• The force of gravity is pulling on the cup.

• The paper cup on a string is pulling on the noodle.

• When the forces are equal, the spaghetti noodle will break.

• Adding nickels to the cup increases the amount of force acting on the noodle.

Tags

NGSS.MS-PS2-2

There are forces acting on objects at all times. Which situations describe equal forces and which describe unequal forces? Write the letter of each answer in the correct box.

Groups:

(a) Equal Forces

,

(b) Unequal Forces

• a jacket hanging on a coat hook

• an apple falling from a tree

• a train slowing down

• a vehicle that continues moving at the same speed and in the same direction

• an object getting knocked over by the wind

• a tug-of-war game where the rope is not moving

• a beach ball floating in a bathtub

Tags

NGSS.MS-PS2-2

Ari conducts an experiment with a cart and a set of weights on a frictionless surface. He observes the time taken for the cart to reach the end of the table as he adds more weights. What is the relationship between the mass added to the cart and the time taken to reach the end?

• The more mass added, the less time it takes.

• The more mass added, the more time it takes.

• The mass added does not affect the time taken.

• The mass added affects the time taken randomly.

Tags

NGSS.MS-PS2-2