Forces Quiz

When air resistance exactly matches the downward force of gravity, a falling object stops accelerating and reaches ______________________.

• terminal velocity

• maximum speed

• constant speed

• zero velocity

Answer explanation

When air resistance equals the force of gravity, the net force is zero, causing the object to stop accelerating. This constant speed is known as terminal velocity, making it the correct answer.

Tags

NGSS.MS-PS2-2

An object at rest tends to remain at rest. This property is called ______________________.

• inertia

• momentum

• velocity

• acceleration

Answer explanation

The correct answer is 'inertia', which is the property of an object to remain at rest or in uniform motion unless acted upon by an external force. This principle is fundamental in Newton's first law of motion.

Only in a vacuum or in space can an object be in ______________________.

• free fall

• constant motion

• static equilibrium

• uniform acceleration

Answer explanation

In a vacuum or space, there is no air resistance, allowing objects to be in free fall. This means they are accelerating towards a mass due to gravity without any opposing forces, unlike the other options.

Tags

NGSS.MS-ESS1-2

A car accelerating from 60 km/h to a constant speed of 80 km/h has increased its ______________________.

• acceleration

• velocity

• momentum

• distance

Answer explanation

The car's speed increased from 60 km/h to 80 km/h, indicating a change in velocity. However, since it is accelerating to a constant speed, the correct term for this change is acceleration, as it refers to the rate of change of velocity.

Tags

NGSS.MS-PS3-1

NGSS.MS-PS3-5

The horizontal movement given to an arrow by a bow is one component of ______________________.

• projectile motion

• linear motion

• circular motion

• rotational motion

Answer explanation

The horizontal movement of an arrow shot from a bow is a key aspect of projectile motion, which describes the motion of an object that is launched into the air and influenced by gravity and initial velocity.

If three balls of steel, rubber, and plastic were dropped at the same time from the same height, which would hit the ground first? (Assume there is no air resistance.)

• All would hit at the same time.

• The rubber ball would hit first.

• The steel ball would hit first.

• The plastic ball would hit first.

Answer explanation

In a vacuum, all objects fall at the same rate regardless of their mass or material. Therefore, the steel, rubber, and plastic balls would all hit the ground at the same time when dropped from the same height.

Assuming 1 kg = 1,000 g, a 5 kg object has less inertia than an object with a mass of

• 4 kg.

• 6,000 g.

• 2 kg.

• 1,500 g.

Answer explanation

Inertia is directly related to mass. A 5 kg object has more inertia than a 4 kg object but less than a 6,000 g (6 kg) object. Therefore, the correct choice is 6,000 g, as it has more mass and thus more inertia.

Newton’s first law of motion states that a moving object, unless it is acted on by an unbalanced force, will

• remain in motion.

• eventually come to a stop.

• change its momentum.

• accelerate.

Answer explanation

Newton's first law states that an object in motion will remain in motion unless acted upon by an unbalanced force. Therefore, the correct answer is that it will remain in motion.

An astronaut uses a jet of nitrogen to maneuver in space. This can be done because of

• orbiting.

• free fall.

• momentum conservation.

• inertia.

Answer explanation

An astronaut uses a jet of nitrogen to change direction in space, demonstrating inertia. Inertia allows objects to maintain their state of motion unless acted upon by an external force, enabling maneuverability in the vacuum of space.

A book weighs 6.0 N. If the acceleration of gravity is 9.8 m/s², what is the mass of the book in kilograms?

• 6.1 kg

• 59 kg

• 1.6 kg

• 0.61 kg

Answer explanation

To find the mass, use the formula: weight = mass × gravity. Rearranging gives mass = weight / gravity. Thus, mass = 6.0 N / 9.8 m/s² = 0.61 kg. Therefore, the correct answer is 0.61 kg.

Tags

NGSS.MS-PS2-2