Unit 8 Honors Physics Review

The SI unit of force, named for the scientist who described the relationship between motion and force, is called the

• Pasteur.

• Einstein.

• Curie.

• Newton.

Answer explanation

The SI unit of force is called the Newton, named after Sir Isaac Newton, who formulated the laws of motion and universal gravitation, establishing the relationship between force and motion.

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

A change in the force of gravity acting on an object will affect the object’s

• mass.

• frictional force.

• weight.

• inertia.

Answer explanation

A change in the force of gravity affects an object's weight, which is the force exerted by gravity on that object. Mass remains constant regardless of gravity, while frictional force and inertia are not directly affected by changes in gravity.

Tags

NGSS.HS-PS2-4

The weight of a 60 kg person is?

• 6.1 N

• 690 N

• 69.8 N

• 588 N

Answer explanation

The weight of a person can be calculated using the formula: weight = mass × gravity. For a 60 kg person, weight = 60 kg × 9.8 m/s² = 588 N. The closest answer choices are 69 N and 69.8 N, which are incorrect. The correct weight is 588 N.

A box with a mass of 10 kg, having a weight of 98 N, is at rest on a table. The normal force action on the box is?

• 9.8 N upward

• 10 N upward

• 98 N upward

• 989 N downward

Answer explanation

The box is at rest, so the normal force must balance the weight. Since the weight is 98 N downward, the normal force is 98 N upward, making the correct answer 98 N upward.

Tags

NGSS.HS-PS2-1

In the absence of an external force, a moving object will

• stop immediately.

• slowdown and eventually come to a stop.

• go faster and faster.

• move with constant velocity

Answer explanation

In the absence of an external force, an object in motion will continue to move with constant velocity, as stated by Newton's first law of motion. This means it will not stop, slow down, or speed up.

Tags

NGSS.HS-PS2-1

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When a woman stands with two feet on a scale, the scale reads 280 N. When she lifts one foot, the scale reads

• less than 280 N

• more than 280 N

• 280 N

Answer explanation

When the woman stands on both feet, the scale reads 280 N, which is her weight. Lifting one foot means only part of her weight is on the scale, resulting in a reading less than 280 N.

Tags

NGSS.HS-PS2-1

Suppose the force of friction on a sliding object is 25 N. The force needed to maintain a constant velocity is

• more than 25 N

• 25 N

• less than 25 N

Answer explanation

To maintain a constant velocity, the applied force must equal the force of friction. Since the friction is 25 N, the force needed is also 25 N, making this the correct choice.

Tags

NGSS.HS-PS2-1

A box is dragged without acceleration in a straight-line path across a level surface by a force of 13 N. What is the frictional force between the box and the surface?

• 13 N

• Less than 13 N

• More than 13 N

• Need more information to say.

Answer explanation

The box is dragged without acceleration, meaning the applied force of 13 N is balanced by the frictional force. Therefore, the frictional force must also be 13 N to maintain a constant velocity.

Tags

NGSS.HS-PS2-1

The movement of an object or a point mass at a constant speed around a circle that has a fixed radius is called uniform:

• circular motion

• parabolic motion

• elliptical motion

• rotational motion

Answer explanation

The correct answer is 'circular motion' because it describes the movement of an object at a constant speed along a circular path with a fixed radius, distinguishing it from other types of motion like parabolic or elliptical.

A sprinter runs at a speed of 3.00 m/s on a circular track that has a radius of 40.00 m. Find the centripetal acceleration of the sprinter.

• 0.225 m/s²

• 4.44 m/s²

• 0.750 m/s²

• 0.0750 m/s²

Answer explanation

Centripetal acceleration (a_c) is calculated using the formula a_c = v²/r. Here, v = 3.00 m/s and r = 40.00 m. Thus, a_c = (3.00)² / 40.00 = 0.225 m/s². Therefore, the correct answer is 0.225 m/s².