Newton's 2nd Law Exam Questions! Quiz

1. A 10N falling object encounters 4N of air resistance. The net force on the object is:

4N

0N

6N

10N

None of the above

When an object is falling, it experiences two forces: gravity pulling it downwards and air resistance pushing against it. In this case, the object has a gravitational force of 10N pulling it downwards, while the air resistance exerts a force of 4N in the opposite direction. The net force is the vector sum of these two forces, which can be calculated by subtracting the smaller force (4N) from the larger force (10N). Therefore, the net force on the object is 10N - 4N = 6N.

Explanation

When an object is falling, it experiences two forces: gravity pulling it downwards and air resistance pushing against it. In this case, the object has a gravitational force of 10N pulling it downwards, while the air resistance exerts a force of 4N in the opposite direction. The net force is the vector sum of these two forces, which can be calculated by subtracting the smaller force (4N) from the larger force (10N). Therefore, the net force on the object is 10N - 4N = 6N.

2. An object is propelled along a straight-line path by force. If the net force were doubled, its acceleration would:

Halve

Double

Quadruple

Stay the same

If the net force acting on an object is doubled, according to Newton's second law of motion, the acceleration of the object will also double. This is because acceleration is directly proportional to the net force applied to an object. Therefore, if the net force is increased by a factor of two, the acceleration will also increase by a factor of two.

Explanation

If the net force acting on an object is doubled, according to Newton's second law of motion, the acceleration of the object will also double. This is because acceleration is directly proportional to the net force applied to an object. Therefore, if the net force is increased by a factor of two, the acceleration will also increase by a factor of two.

3. The force of friction on a sliding object is 10 newtons. The applied force needed to maintain a constant velocity is:

Less than 10N

More than 10N

10N

The applied force needed to maintain a constant velocity is 10N. This is because the force of friction on a sliding object is equal in magnitude and opposite in direction to the applied force. In order for the object to continue moving at a constant velocity, the applied force must balance out the force of friction. Therefore, the applied force needs to be equal to the force of friction, which is 10N in this case.

Explanation

The applied force needed to maintain a constant velocity is 10N. This is because the force of friction on a sliding object is equal in magnitude and opposite in direction to the applied force. In order for the object to continue moving at a constant velocity, the applied force must balance out the force of friction. Therefore, the applied force needs to be equal to the force of friction, which is 10N in this case.

4. One object had twice as much mass as another object. The first object also has twice as much:

Volume

Gravitational acceleration

Inertia

Velocity

Inertia is the property of an object that resists changes in its motion. When an object has more mass, it also has more inertia. This means that it will be more resistant to changes in its velocity or direction of motion. In this scenario, since the first object has twice as much mass as the second object, it will also have twice as much inertia. The other options, such as volume, gravitational acceleration, and velocity, are not directly related to an object's mass and therefore do not necessarily increase in the same proportion.

Explanation

Inertia is the property of an object that resists changes in its motion. When an object has more mass, it also has more inertia. This means that it will be more resistant to changes in its velocity or direction of motion. In this scenario, since the first object has twice as much mass as the second object, it will also have twice as much inertia. The other options, such as volume, gravitational acceleration, and velocity, are not directly related to an object's mass and therefore do not necessarily increase in the same proportion.

5. Which of the following has zero acceleration? An object

Moving at a constant velocity

At rest

At equilibrium

All of the above

All of the above options have zero acceleration. An object moving at a constant velocity has zero acceleration because its speed and direction do not change. An object at rest also has zero acceleration because it is not moving. An object at equilibrium, where all the forces acting on it are balanced, also has zero acceleration because there is no net force acting on it. Therefore, all three options have zero acceleration.

Explanation

All of the above options have zero acceleration. An object moving at a constant velocity has zero acceleration because its speed and direction do not change. An object at rest also has zero acceleration because it is not moving. An object at equilibrium, where all the forces acting on it are balanced, also has zero acceleration because there is no net force acting on it. Therefore, all three options have zero acceleration.

6. An object weighs 30N on earth. A second object weighs 30N on the moon. Which the greater mass? (Note: due to its size, the moon has less gravity than the earth.)

Object on moon

Object on earth

Same mass

Depends on air resistance

Weight is the force of gravity acting on an object's mass. Mass is an intrinsic property of an object and remains constant regardless of location. Since the moon has less gravity than Earth, an object weighing 30N on the moon must have a greater mass than an object weighing 30N on Earth. This is because a larger mass is needed on the moon to experience the same gravitational force (weight) as a smaller mass on Earth.

Explanation

Weight is the force of gravity acting on an object's mass. Mass is an intrinsic property of an object and remains constant regardless of location. Since the moon has less gravity than Earth, an object weighing 30N on the moon must have a greater mass than an object weighing 30N on Earth. This is because a larger mass is needed on the moon to experience the same gravitational force (weight) as a smaller mass on Earth.

7. Compared to a 1kg block of solid iron, a 2kg block of solid iron has twice as much:

Inertia

Mass

Volume

All

None

A 2kg block of solid iron has twice as much inertia, mass, and volume compared to a 1kg block of solid iron. Inertia is the resistance of an object to changes in its motion, and since the 2kg block has more mass, it will have more inertia. Mass is the amount of matter in an object, and the 2kg block has double the mass of the 1kg block. Volume refers to the amount of space an object occupies, and the 2kg block will also have twice the volume of the 1kg block. Therefore, all of these properties are doubled in the 2kg block compared to the 1kg block.

Explanation

A 2kg block of solid iron has twice as much inertia, mass, and volume compared to a 1kg block of solid iron. Inertia is the resistance of an object to changes in its motion, and since the 2kg block has more mass, it will have more inertia. Mass is the amount of matter in an object, and the 2kg block has double the mass of the 1kg block. Volume refers to the amount of space an object occupies, and the 2kg block will also have twice the volume of the 1kg block. Therefore, all of these properties are doubled in the 2kg block compared to the 1kg block.

8. A 10kg block is pushed across a horizontal surface with a horizontal force of 20N against a friction force of 10N. The acceleration of the block in meters per second per second is:

1

5

2

10

The acceleration of an object can be calculated using Newton's second law of motion, which states that the acceleration is equal to the net force acting on the object divided by its mass. In this case, the net force is the force pushing the block (20N) minus the friction force (10N), resulting in a net force of 10N. Since the mass of the block is 10kg, the acceleration can be calculated as 10N/10kg = 1 m/s^2. Therefore, the correct answer is 1.

Explanation

The acceleration of an object can be calculated using Newton's second law of motion, which states that the acceleration is equal to the net force acting on the object divided by its mass. In this case, the net force is the force pushing the block (20N) minus the friction force (10N), resulting in a net force of 10N. Since the mass of the block is 10kg, the acceleration can be calculated as 10N/10kg = 1 m/s^2. Therefore, the correct answer is 1.

9. A 10kg block with an initial velocity of 10m/s slides 10m across a horizontal surface and comes to rest. It takes the block 2 seconds to stop. The stopping force acting on the block is about:

5N

10N

25N

50N

The stopping force acting on the block can be calculated using the equation F = m * a, where F is the force, m is the mass, and a is the acceleration. In this case, the block comes to rest, so its final velocity is 0 m/s. Using the equation v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time taken, we can find the acceleration. Rearranging the equation, we have a = (v - u) / t. Plugging in the values, we get a = (0 - 10) / 2 = -5 m/s^2. Now, we can use Newton's second law to find the stopping force (F):

F=ma

Where:

m is the mass of the block,

a is the acceleration.

F=(10kg)×(−5m/s2)

F=−50N

The negative sign in the force indicates that the force is acting in the opposite direction to the initial velocity, representing the force that is slowing down the block. So, the stopping force acting on the block is 50 N.

Explanation

The stopping force acting on the block can be calculated using the equation F = m * a, where F is the force, m is the mass, and a is the acceleration. In this case, the block comes to rest, so its final velocity is 0 m/s. Using the equation v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time taken, we can find the acceleration. Rearranging the equation, we have a = (v - u) / t. Plugging in the values, we get a = (0 - 10) / 2 = -5 m/s^2. Now, we can use Newton's second law to find the stopping force (F):

F=ma

Where:

m is the mass of the block,

a is the acceleration.

F=(10kg)×(−5m/s2)

F=−50N

The negative sign in the force indicates that the force is acting in the opposite direction to the initial velocity, representing the force that is slowing down the block. So, the stopping force acting on the block is 50 N.

10. A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is:

Equal to the weight of the puck

The weight of the puck divided by the mass of the puck

The mass of the puck multiplied by 9.8 m/s

Zero newtons

The correct answer is zero newtons because if ice friction and air resistance are neglected, there are no external forces acting on the puck to slow it down or speed it up. Therefore, no force is required to keep the puck sliding at a constant velocity.

Explanation

The correct answer is zero newtons because if ice friction and air resistance are neglected, there are no external forces acting on the puck to slow it down or speed it up. Therefore, no force is required to keep the puck sliding at a constant velocity.