Newton's Laws Forces Review F=M x A, W=M x G

Front

Which object in the table below would require the most force to begin moving?

Back

The bowling ball requires more force because mass is directly related to inertia.

Answer explanation

The bowling ball requires more force to begin moving because it has greater mass, which means it has more inertia. Inertia is the resistance of an object to changes in its state of motion, and more mass results in more inertia.

Front

What will happen to the cart’s acceleration during Trial #3 based on the experiment data?

Back

Acceleration decreases to 2 m/s². Explanation: As force decreases the acceleration will also decrease.

Answer explanation

In Trial #3, as the force applied to the cart decreases, the acceleration will also decrease. Therefore, the predicted acceleration is 2 m/s², consistent with Newton's second law, which states that acceleration is directly proportional to force.

Front

Anna, whose mass is 35 kg, and her dad, whose mass is 68 kg, stand face to face on roller skates. When they push off each other, Anna rolls away with an acceleration of 3 m/s². Use Newton’s Laws to explain the difference between Anna’s acceleration and her dad’s acceleration.

Back

Anna’s acceleration is greater than her dad’s acceleration because Anna has less mass but experiences the same strength force as her dad.

Answer explanation

Anna's acceleration is greater than her dad's because she has less mass. According to Newton's second law (F=ma), for the same force exerted, a smaller mass results in a greater acceleration.

Front

How does an astronaut’s mass on Earth compare to her mass in space? In space she is far away from any other objects with mass, and she experiences little to no gravitational force?

Back

The astronaut’s mass is the same in space as it is on Earth.

Answer explanation

An astronaut's mass is a measure of the amount of matter in her body, which remains constant regardless of location. Therefore, her mass is the same in space as it is on Earth.

Front

Statement of Newton’s Second Law:
1. F = ma
2. Objects will not change velocity without an outside force.
3. Objects with large accelerations have large amounts of mass.
4. For every force there is an equal and opposite force.

Back

F = ma

Answer explanation

The correct statement of Newton’s Second Law is F = ma, which defines the relationship between force (F), mass (m), and acceleration (a). The other options describe different principles of physics.

Front

Which of the following is a statement of Newton’s third law?

Back

For every force there is an equal and opposite force.

Answer explanation

Choice C correctly states Newton's third law, which asserts that for every action force, there is an equal and opposite reaction force. The other options do not represent this fundamental principle of motion.

Front

A force of 15.0 N is applied to a rolling cart to make it accelerate 2.5 m/s^2. What is the mass of the cart?

Back

6 kg

Answer explanation

Using Newton's second law, F = ma, we can rearrange to find mass: m = F/a. Here, F = 15.0 N and a = 2.5 m/s². Thus, m = 15.0 N / 2.5 m/s² = 6 kg. Therefore, the mass of the cart is 6 kg.

Front

In the absence of air resistance, how would the acceleration of a 1.5 kg book and the acceleration of a 15 kg rock compare if the objects were dropped from the same height?

Back

The acceleration of the book and rock would be the same.

Answer explanation

In the absence of air resistance, all objects fall at the same rate regardless of their mass. Therefore, the acceleration of the 1.5 kg book and the 15 kg rock would be the same.

Front

A man weighs 500 N on Earth. What is man's mass?

Back

51.0 kg

Answer explanation

To find mass, use the formula: weight = mass × gravity. On Earth, gravity is approximately 9.8 m/s². Thus, mass = weight / gravity = 500 N / 9.8 m/s² ≈ 51.0 kg. Therefore, the correct answer is 51.0 kg.

Front

A person pulls up on a bucket with a force of 45 N. The bucket and water have a mass of 4.0 kg. What is the net force on the bucket?

Back

5.8 N upwards

Answer explanation

First, calculate the weight of the bucket: weight = mass × gravity = 4.0 kg × 9.8 m/s² = 39.2 N downwards. The net force is the applied force minus the weight: 45 N - 39.2 N = 5.8 N upwards.