Speed, Motion & Acceleration 8th grade Science

A local school activity bus travels North to Denton to take students on a tour of the University of North Texas. The trip from the school to Denton is 66 kilometers. The bus travels for 56 minutes before it arrives at the UNT campus. Which of the following best represents the speed of the bus for this campus visit trip?

• 1.18 km/min North

• 2.0 km/min South

• 1.2 km/hr

• 1.18 km/min

Louis was traveling south with his family from San Antonio to Mexico. Louis used his phone to check how long it would to get there. His phone read that it would take about 4 hours to travel the 270 miles. What would the velocity of Louis's car have to be in order to cover that distance in that amount of time?

• 67.5 mi/hr²

• 67.5 mi/hr

• 67.5 mi/hr south

• 67.5 mi/hr² south

When a car suddenly stops, the objects in the back seat are thrown forward. This is explained by-

• Newton's 1st Law

• Newton's 2nd Law

• Newton's 3rd Law

• The Universal Law of Gravitation

A train containing four cars is accelerating at 15 m/s² before it comes to an abrupt stop at the end of the track. The mass of one car is 200 kg. How much force was exerted on the train to bring it to a stop?

• 3000N

• 800N

• 12000N

• 60N

Tags

NGSS.MS-PS2-2

A balloon rocket is on a string. When the student lets the balloon go the balloon propels forward. What is the action-reaction that causes the forward motion.

• the balloon releases air; the balloon

• the balloon releases air; the string

• the elasticity of the balloon; the string

• the balloon releases air; the air

Tags

NGSS.MS-PS2-1

While in outer space a rocket engine is able to produce thrust on a spacecraft. Identify the correct action-reaction pair which allows the spacecraft to propel itself upward.

• rocket engine-spacecraft

• rocket engine nozzle-exhaust gasses

• exhaust gasses-ground

• exhaust gasses-air behind the spacecraft

Which of the following best illustrates an application of Newton’s First Law (also called the Law of Inertia)?

• A passenger not wearing a seatbelt is ejected from an automobile during a severe crash.

• Dinner plates remain on a table when a slick tablecloth is pulled out from underneath them.

• An ice hockey puck continues sliding across the relatively frictionless ice until it comes into contact with a wall or a player’s stick.

• None of these are examples of the Newton's First Law.

The picture above illustrates the horizontal forces acting on a car. The car’s engine force pushes forward, while friction between the tires and the road, along with wind resistance drag at the car in the backwards direction. Which of the following must be true about these forces if the car is driving forward on a level road at a constant speed of 70 miles per hour?

• The force of the engine forward must be greater than the force of gravity acting on the car.

• The force of the engine forward must be equal to the combined resistance forces.

• The force of the engine forward must be greater than the combined forces of friction backward.

• The force of the engine forward must be less than the combined forces of friction backward.

Tags

NGSS.MS-PS2-2

The kids slide their sled down a hill during the winter break. While it is on the hill, gravity acts on the sled as an unbalanced force. Which of the following graphs best illustrates the sleds velocity while it is on the hill?

• 
• 
• 
• 

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

NGSS.MS-PS2-4

NGSS.MS-PS3-1

John is an outstanding forward on his club select soccer team. He is known for his ball control and speed. After a game, he often makes a sketch of moves that were successful. The dotted line on his sketch shows the magnitude and the direction the ball was moving when he kicked it. The magnitude and direction of his kick is the solid arrow.

How did the motion of the ball change when John kicked it?

• The ball came to a complete stop.

• The ball continued moving in the same direction and its speed decreased.

• The ball continued moving in the same direction and its speed increased.

• The ball changed directions and its speed increased.

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2