Unit 2 Review

A player kicks a stationary soccer ball that has a mass of 1.5 kg causing the ball to accelerate at a rate of 12 m/s/s. What waws the net force applied to the ball?

• 18 N
• 6 N
• 12 N
• 24 N

Answer explanation

The problem is solved using the equation F=ma

F= (1/5kg)(12 m/s/s)

F= 6kg x m/s/s

F=6N

Tags

NGSS.MS-PS2-2

After jumping out of an airplane and prior to deploying her parachute, a sky diver with a mass of 88kg jumped out of an airplane reached a constant velocity of 8 m/s downward. What is the net force acting on the sky diver?

• 10 N
• 8 N

• 4 N

• 0 N

Answer explanation

The skydiver was moving at a constant velocity, which means her acceleration was zero. According to the equations F=ma:

F = (82kg) (0 m/s/s)

F = 0kg x m/s/s = 0 N

Tags

NGSS.MS-PS2-2

Based on Newton's Second Law of Motion, how is the force due to gravity acting on an object calculated?

• The acceleration due to gravity is divided by the mass of the object.

• The mass of the object is divided by the acceleration due to gravity.

• The mass of the object is multiplied by the acceleration due to gravity.

• The force due to gravity is a constant that cannot be calculated.

Answer explanation

According to the equation F=ma, the gravitational force is equal to the product of the object's mass and the acceleration due to gravity.

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

A 900 kg car experiences an acceleration of 10 m/s/s after a 9000 N force is applied. Which statements accurately describe the outcome if a 1200 kg truck were used in place of the car. Select two choice.

• The truck would require less total force to achieve the same acceleration.

• A force of 10,800 N would be required to achieve the same acceleration.

• A force of 12,000 N would be required to achieve the same acceleration.

• If the same force were applied, the acceleration would be 12 m/s/s.

• If the same force were applied, the acceleration would be 7.5 m/s/s

Answer explanation

Using the equation F=ma:

9000 N = 1200 x 7.5

The same force would result in an acceleration of 7.5 m/s/s or

12000 N =1200 x 10

A force of 12,000 N is required to achieve the same acceleration (of 10 m/s/s).

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

A tennis ball (0.06 kg), a soccer ball (0.8 kg). and a bowling ball (8 kg) have the masses shown. If a net force of 12 N is applied to each ball, which statement accurately describes the balls' rates of acceleration?

• The acceleration will be the same for all three balls.

• The soccer ball will have the greatest acceleration.

• The bowling ball will have the greatest acceleration.

• The tennis ball will have the greatest acceleration.

Answer explanation

Based on the equation F=ma, with constant force e applied, the object with the smallest mass will experience the greatest acceleration.

Tags

NGSS.MS-PS2-2

Jerry and Chrissy are hitting baseballs. They set the baseballs on tees, swing their bats to hit the baseballs, and the ball exerts a force back on the bat as they make contact. What is true about the force on the bat?

• The force on the bat is less than the force on the baseball

• The force on the bat is equal to the force on the baseball.

• The force on the bat is more than the force on the baseball.

• The force on the bat is nonexistent, there is only force on the baseball.

Answer explanation

The force on the bat is equal to the force on the baseball is the correct answer because for every action force there is an equal and opposite reaction force. So the force on the bat is less than the force on the baseball, and the force The force on the bat is equal to the force on the baseball is the correct answer because for every action force there is an equal and opposite reaction force.

Tags

NGSS.MS-PS2-1

Match each sentence with the correct Newton's law of motion. You will use one of Newton's Laws twice.

• Action-Reaction Law (3rd Law of Motion)

• A rocket is launched into space as the force of exploding gases downward pushes the rocket upward.

• F=ma (2nd Law of Motion)

• Once it is in space, the engines are switched off and it will keep on moving at a constant speed and direction.

• Law of Inertia (1st Law of Motion)

• The amount of force produced by the rocket will depend on the mass of rocket fuel that is burned and how fast the gas leaves the rocket.

• Action-Reaction Law (3rd Law of Motion)

• The motion of the rocket is equal and opposite to the thrust from the engine.

Answer explanation

A rocket is launched into space as the force of the exploding gases downward pushes the rocket upward and the motion of the rocket is equal and opposite to the thrust from the engine are both examples of Newton's 3rd Law, for every action force there is an equal and opposite reaction force. The amount of force produced by the rocket will depend on the mass of rocket fuel that is burned and how fast the gas leaves the rocket is an example of Newton's Second Law, force equals mass times acceleration. Once it is in space, the engines are switched off and it will keep moving at a constant speed and direction is an example of Newton's Firsts Law of Inertia, an object at rest will stay at rest and an object in motion will stay in motion unless acted on by an unbalanced force. If the astronauts want to change the direction of the rocket, they need to start an engine. This will then apply a force on the rocket and will change its direction.

Tags

NGSS.MS-PS2-2

Earth's tectonic plates have moved throughout Earth's history. Use the image to describe how Newton's First Law explains how the force of the land mass we know as India compared to the force of the Eurasian plate on India.

Answer explanation

Newton's First law of Inertia, an object at rest and an object in motion will stay in motion unless acted on my an unbalanced force. Both the India land mass and the Eurasia plate continue to stay in motion and do so unless acted upon by an unbalanced force (each other). They will continue to stay in motion even after they are together.

Tags

NGSS.MS-PS2-4

NGSS.MS-PS2-5

What is the net force acting on a 1200 kg cat that is accelerating east at a rate of 30 m/s/s?

• 36 N

• 360 N

• 3600 N

• 36,000 N

Answer explanation

Using the formula F=ma

F = (1200)(30)

F = 36000 N

Tags

NGSS.MS-PS2-2

Using Newton's Second Law of motion, explain why a bus requires a greater distance to come to a complete stop compared to a car traveling the same speed.

Answer explanation

The force required to top (negative acceleration) for the bus would be much greater than the force required for the car. Taking a longer time to stop means rate of (negative) acceleration is lower and therefore force required is reduced.

Tags

NGSS.HS-PS2-1