Chapter 4: Newton's Second Law Of Motion, Force And Acceleration

When a falling object has reached its terminal velocity, its acceleration becomes zero. Terminal velocity is the maximum velocity that an object can attain while falling through a fluid, such as air. Initially, the object accelerates due to the force of gravity. However, as the object gains speed, the upward drag force exerted by the fluid increases, eventually balancing out the force of gravity. At this point, the net force on the object becomes zero, resulting in zero acceleration. Therefore, the correct answer is zero.

When the net force on an object is zero, it means that all the forces acting on the object are balanced and cancel each other out. In this case, the object's acceleration will be zero. This is because acceleration is directly proportional to the net force acting on an object according to Newton's second law of motion. If the net force is zero, there is no unbalanced force to cause acceleration, resulting in a zero acceleration.

The magnitude of the resultant force on the object is 5 N because the forces pulling in opposite directions will cancel each other out partially. The northward force of 10 N will be partially counteracted by the southward force of 15 N, resulting in a net force of 5 N in the northward direction.

When the man stands at rest on two bathroom scales, his weight is distributed evenly over both scales. This means that each scale is supporting half of his weight. Since his weight is 800 N, each scale will read half of that, which is 400 N. Therefore, the reading on each scale is 400 N.

When a woman stands at rest with both feet on a scale, the scale reads 500 N because it is measuring the force exerted by her body on the scale. When she gently lifts one foot, the scale will still read 500 N because the force exerted by her body on the scale remains the same. The scale is measuring the total force exerted by the woman's body, not just the force exerted by her feet.

At the very top of its trajectory, the rock is momentarily at rest before it starts to fall back down. This means that its acceleration is zero, and according to Newton's second law, the net force acting on an object is equal to its mass multiplied by its acceleration. Since the acceleration is zero, the net force on the rock must also be zero. However, the weight of an object is the force due to gravity acting on it, and it always acts downwards. Therefore, at the very top of its trajectory, the net force on the rock is equal to its weight.

A force is considered a vector quantity because it has both magnitude and direction. Magnitude refers to the size or strength of the force, while direction indicates the path or orientation in which the force is applied. These two components are essential in fully describing a force and understanding its effects on an object or system.

The weight of an object is the force exerted on it due to gravity. The weight is directly proportional to the mass of the object. In this case, the bag of groceries has a mass of 10 kilograms, so its weight can be calculated using the formula weight = mass x acceleration due to gravity. The acceleration due to gravity is approximately 9.8 m/s^2. So, weight = 10 kg x 9.8 m/s^2 = 98 N. Therefore, the weight of the bag of groceries is about 100 N.

The weight of an object is the force exerted on it due to gravity. On Earth's surface, the acceleration due to gravity is approximately 9.8 m/s^2. Using the formula weight = mass x acceleration due to gravity, we can calculate the weight of a 1-kg mass to be 9.8 N.

The wagon's acceleration can be calculated using Newton's second law, which states that the force applied to an object is equal to the mass of the object multiplied by its acceleration. In this case, the force applied to the wagon is 30 N and the mass of the wagon is 10 kg. Therefore, the acceleration of the wagon is 30 N / 10 kg = 3.0 m/s^2.

When an object is falling, it experiences two forces: gravity pulling it downward and air resistance pushing it upward. In this case, the object encounters 10 N of air resistance, which cancels out the 10 N force of gravity. Therefore, the net force on the object is 0 N.

A kilogram is a measure of an object's mass. Mass refers to the amount of matter in an object, and it remains the same regardless of the object's location or the force acting on it. Weight, on the other hand, is the force exerted on an object due to gravity and can vary depending on the object's location. Size is a measure of an object's dimensions and is unrelated to mass. Therefore, the correct answer is mass.

The applied force needed to maintain a constant velocity is equal to the force of friction. In this case, the force of friction is 10 newtons, so the applied force needed to maintain a constant velocity is also 10 newtons.

An object following a straight-line path at constant speed has zero acceleration. This is because acceleration is the rate of change of velocity, and if the object is moving at a constant speed, its velocity is not changing. Therefore, there is no acceleration.

If less horizontal force is applied to a sliding object than is needed to maintain a constant velocity, the object eventually slides to a stop. This is because the force applied is not enough to counteract the opposing forces such as friction, air resistance, or any other resistance that may be acting on the object. As a result, the object gradually loses its velocity and comes to a stop.

When air resistance equals the weight of the sack (200 N), the net force on the sack becomes zero. According to Newton's second law of motion, F = ma, where F is the net force, m is the mass, and a is the acceleration. Since the net force is zero, the acceleration of the sack is also zero. Therefore, the correct answer is 0.

The deceleration of the car can be calculated using the formula: deceleration = change in velocity / time. In this case, the change in velocity is from 22 m/s to 0 m/s, which is a decrease of 22 m/s. The time taken for this change is 0.1 seconds. Therefore, the deceleration is 22 m/s / 0.1 s = 220 m/s^2.

An automobile battery has a greater mass compared to a king-size pillow. This is because automobile batteries are generally made of heavy materials such as lead and have a larger size and weight compared to a pillow, which is typically filled with lightweight materials like feathers or synthetic fibers. Therefore, the battery would have a greater mass.

When the rock is halfway to the top of its path, it has already reached its maximum height and is momentarily at rest before falling back down. At this point, the net force acting on the rock is equal to its weight, which is 9.8 N. This is because the only force acting on the rock is gravity, which pulls it downward with a force equal to its weight. Therefore, the correct answer is 9.8 N.

To provide equal horizontal acceleration to both blocks, we need to apply a force that overcomes the inertia of each block. The force required to overcome inertia is directly proportional to the mass of the object. Since the 10-N block is heavier than the 1-N block, it has more inertia and therefore requires a greater force to accelerate it. Therefore, we would have to push with 10 times as much force on the heavier block.

The acceleration of the jumbo jet can be calculated using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the total force exerted by the four engines is 50,000 N * 4 = 200,000 N. Dividing this force by the mass of the jet (100,000 kg) gives us the acceleration, which is 200,000 N / 100,000 kg = 2 meters per second per second.

When a skydiver falls head first, their body position creates the least amount of air resistance. This allows them to reach their maximum speed, known as terminal velocity, more quickly. By reducing air resistance, the skydiver can accelerate faster and reach a higher velocity compared to other body positions.

If an object of constant mass experiences a constant net force, according to Newton's second law of motion, the object will have a constant acceleration. This is because the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Therefore, if the mass remains constant and the net force is constant, the object will experience a constant acceleration.

The net force on the object is 6 N because it is the difference between the force of gravity (10 N) and the force of air resistance (4 N). The net force is the overall force acting on the object, taking into account both the forces acting in the same direction and those acting in opposite directions. In this case, the force of gravity is acting downwards, while the force of air resistance is acting upwards. Therefore, the net force is the difference between these two forces, resulting in a net force of 6 N acting downwards on the object.

To equally accelerate a 10-kg brick, one would have to push with 10 times as much force. This is because according to Newton's second law of motion, the force applied on an object is directly proportional to its mass and acceleration. In this case, the mass of the 10-kg brick is 10 times greater than the 1-kg brick, so to achieve the same acceleration, the force applied must also be 10 times greater.

The mass of an object can be determined using the formula F = ma, where F is the force exerted on the object and a is the acceleration. In this case, the force exerted by the tow truck is 3000 N and the acceleration of the car is 2 m/s^2. Plugging these values into the formula, we get 3000 N = m * 2 m/s^2. Solving for m, we find that the mass of the car is 1500 kg.

The skydiver is experiencing air resistance, which is acting in the opposite direction to the force of gravity. The acceleration of the skydiver can be determined using Newton's second law of motion, which states that force is equal to mass times acceleration. The force of gravity acting on the skydiver can be calculated using the formula F = mg, where m is the mass of the skydiver and g is the acceleration due to gravity. In this case, the force of gravity is 100 kg * 9.8 m/s^2 = 980 N. Since the air resistance is 500 N, the net force acting on the skydiver is 980 N - 500 N = 480 N. Using Newton's second law, we can determine the acceleration of the skydiver: 480 N = 100 kg * a, where a is the acceleration. Solving for a gives us a = 480 N / 100 kg = 4.8 m/s^2. To express the acceleration in terms of g, we divide by the acceleration due to gravity: 4.8 m/s^2 / 9.8 m/s^2 = 0.49 g. Since the question asks for the acceleration in terms of g, the correct answer is 0.5 g.

The correct answer is "the gravitational attraction force between you and the Earth." Weight is the force exerted on an object due to gravity, and it is directly proportional to an object's mass. Therefore, your weight is equal to the gravitational attraction force between you and the Earth.

The light woman will get to a state of zero acceleration first because her smaller mass means that there is less force acting on her due to gravity. This allows her to reach a state of zero acceleration more quickly than the heavy man.

The weight of an object is equal to the force of gravity acting on it, which is given by the equation weight = mass * acceleration due to gravity. In this case, the turtle weighs 10 N, which means the force of gravity acting on it is 10 N. Since the acceleration due to gravity is approximately 9.8 m/s^2, we can rearrange the equation to solve for mass: mass = weight / acceleration due to gravity. Substituting the given values, we find that the mass of the turtle is approximately 1 kg.

An object's weight is a measure of the force exerted on it due to gravity. The unit of measurement for force is newtons. Therefore, it is appropriate to express an object's weight in newtons. Meters, kilograms, and cubic centimeters are units of length, mass, and volume respectively, and are not suitable for measuring weight.

The correct answer is less than 5 s. This is because air resistance slows down the upward motion of the ball, causing it to take longer to reach its maximum height. Therefore, the time taken for the ball to just go up is less than the total time of 10 seconds.

The force of friction between the block and the surface is 6 N because the block is being dragged without acceleration. According to Newton's first law of motion, if an object is moving with constant velocity, the net force acting on it must be zero. In this case, the force of friction is equal in magnitude and opposite in direction to the applied force of 6 N, resulting in a net force of zero. Therefore, the force of friction must also be 6 N.

The mass of an object remains the same regardless of its location. Therefore, the mass of a certain object on the moon would be the same as its mass on Earth.

When the parachutist opens his chute, he experiences an air resistance force of 800 N. The force of air resistance acts in the opposite direction to the force of gravity, which is 500 N downward. The net force on an object is the vector sum of all the forces acting on it. In this case, the net force is the difference between the force of gravity and the force of air resistance, which is 500 N downward minus 800 N upward. Thus, the net force on the parachutist is 300 N upward.

At terminal velocity, the air resistance acting on the skydiver is equal to the weight of the skydiver. This is because the force of gravity pulling the skydiver downwards is balanced by the force of air resistance pushing upwards. Since the skydiver weighs 500 N, the air resistance on the diver is also 500 N.

All of these options have zero acceleration. An object at rest has zero velocity and therefore zero acceleration. An object moving at constant velocity also has zero acceleration because its velocity is not changing. An object in mechanical equilibrium has zero net force acting on it, which means it has zero acceleration. Therefore, all of these options have zero acceleration.

When the mass of an object does not change, a constant net force on the object will produce a constant acceleration. This is explained by Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. Since the mass is constant, a constant net force will result in a constant acceleration. Velocity, on the other hand, is the rate at which an object's position changes, and it is not directly affected by a constant net force. Therefore, the correct answer is acceleration.

When a rock is thrown vertically into the air, it experiences a constant acceleration due to gravity. This acceleration is always directed downwards and has a magnitude of 9.8 meters per second per second. At the top of its path, the rock momentarily comes to a stop before starting to fall back down. During this brief moment, the rock's velocity is zero, but its acceleration is still 9.8 meters per second per second, as gravity continues to act on it. Therefore, the correct answer is 9.8.

When a particle is being accelerated through space by a 10-N force and encounters a second force of 10 N in the opposite direction, the two forces cancel each other out. This means that the net force acting on the particle is zero. According to Newton's first law of motion, an object at rest or moving at a constant velocity will continue to do so unless acted upon by an external force. Therefore, the particle will continue at the speed it had when it encountered the second force.

When you relax at rest with your left foot on one bathroom scale and your right foot on a similar scale, each of the scales may indicate exactly half your weight if your weight is evenly distributed between both feet. However, if your weight is not evenly distributed, the scales may indicate part of your total weight but not necessarily half of it. Additionally, if there is any imbalance or inconsistency in the scales, they may indicate different values that will equal your weight when added together. Therefore, any of the above options may be correct depending on the specific circumstances.

The correct answer is that the mass of the car is independent of gravity. This means that the amount of matter in the car, which determines its inertia and resistance to acceleration, remains the same regardless of the gravitational force acting on it. Therefore, the car would require the same amount of force to accelerate on the moon as it would on Earth, despite the difference in gravity.

If the net force acting on an object is doubled, according to Newton's second law of motion (F = ma), the acceleration of the object would also double. This is because acceleration is directly proportional to the force applied on an object. Therefore, if the force is doubled, the acceleration will also be doubled.

To parachute at equal terminal velocities, the larger person needs a larger parachute. This is because the larger person has a greater mass, which means they experience a greater gravitational force pulling them downward. To counteract this force and reach the same terminal velocity as the smaller person, the larger person needs a larger parachute with more surface area to generate a greater air resistance force. This will balance out the gravitational force and allow both individuals to descend at the same speed.

As the skydiver jumps from a high-flying plane, her velocity of fall initially increases due to the force of gravity. However, as she continues to fall, air resistance starts to play a role. The upward force of air resistance opposes the downward force of gravity, causing a net force that is less than the force of gravity alone. This results in a decrease in the acceleration of the skydiver. Therefore, her acceleration decreases as her velocity of fall increases.

When a ball is thrown vertically into the air, the force of air resistance acts against its motion. As the ball rises, air resistance slows it down, causing its speed to decrease. When the ball reaches its peak height and starts to fall, air resistance continues to act in the opposite direction, further reducing its speed. Therefore, when the ball returns to its starting level, its speed is less than its initial speed.

The newton is a unit of force. Force is a physical quantity that can cause an object to accelerate or deform. It is measured in newtons, and it is the product of mass and acceleration. In other words, force is the push or pull that one object exerts on another object. The newton is named after Sir Isaac Newton, a renowned physicist and mathematician who made significant contributions to the study of motion and force.

The force required to maintain an object at a constant velocity in free space is equal to zero because according to Newton's first law of motion, an object at rest or in motion will remain in that state unless acted upon by an external force. In free space, where there is no friction or other forces acting on the object, no external force is needed to keep it moving at a constant velocity.

The car experiences a braking force of 10,000 N and comes to a stop in 6 seconds. To find the initial speed of the car, we can use the equation:

Force = mass x acceleration

Rearranging the equation, we get:

Acceleration = Force / mass

Plugging in the given values, we have:

Acceleration = 10,000 N / 2000 kg = 5 m/s^2

Now, we can use the equation of motion:

Final velocity = Initial velocity + (acceleration x time)

Since the final velocity is 0 m/s (the car comes to a stop), we can rearrange the equation to solve for the initial velocity:

Initial velocity = - (acceleration x time)

Plugging in the values, we get:

Initial velocity = - (5 m/s^2 x 6 s) = -30 m/s

Since the speed cannot be negative, the correct answer is none of these.

When the brakes are released, the car tends to continue moving at the same speed it was at before, which in this case is 40 km/h. This is because there are no other forces acting on the car to slow it down or speed it up. The car will maintain its velocity unless acted upon by an external force, such as friction or gravity. Therefore, the correct answer is "continue moving at 40 km/h."