Read the scenario.
A cyclist is riding his bike at a constant speed of 5 m/s, and experiences a frictional force between the bike and sidewalk of 100 N. The cyclist then changes his speed to 10 m/s.
What effect does this increase in speed have on the frictional force between the bike and sidewalk?
The frictional force between the bike and sidewalk stays the same because speed does not affect frictional force.
The frictional force increases, but does not double because although friction increases with increasing speed, it does not increase as fast.
The frictional force increases and approximately doubles because the frictional force is directly proportional to the speed of the bike.
needs to be one of the answers shown
The frictional force between the bike and sidewalk stays the same because speed does not affect frictional force.
A ball moves along a smooth metal surface while an identical ball moves along concrete.
Which surface exerts a smaller amount of frictional force on the ball?
Responses
The concrete surface exerts less frictional force on the ball because there are fewer bumps and irregularities on the concrete than there are on the metal.
The concrete surface exerts less frictional force on the ball because there are fewer bumps and irregularities on the concrete than there are on the metal.
The concrete and metal surfaces exert the same amount of frictional force on the ball because they are both solid surfaces.
The concrete and metal surfaces exert the same amount of frictional force on the ball because they are both solid surfaces.
Neither concrete nor metal exert any friction on the ball because these two surfaces never result in a frictional force on any object.
Neither concrete nor metal exert any friction on the ball because these two surfaces never result in a frictional force on any object.
The metal surface exerts less frictional force because there are fewer bumps and irregularities on it than there are on the concrete.
The metal surface exerts less frictional force because there are fewer bumps and irregularities on it than there are on the concrete.
Study the scenario.
An object is at rest. At five seconds, someone comes over and pushes the object forward with a force of 10 N. After it is pushed, the object is still at rest.
Which of the following choices describes how static equilibrium could have been achieved when the object was pushed?
Responses
A force of exactly 10 N was exerted straight down on the object, countering the normal force.
A force of exactly 10 N was exerted straight down on the object, countering the normal force.
A force greater than 10 N was exerted in a forward direction on the object at exactly five seconds so that the forces were balanced, and the object remained at rest.
A force greater than 10 N was exerted in a forward direction on the object at exactly five seconds so that the forces were balanced, and the object remained at rest.
A force greater than 10 N was exerted straight down on the object, countering the normal force.
A force greater than 10 N was exerted straight down on the object, countering the normal force.
A backward force of 10 N was exerted on the box at exactly five seconds so that the forces were balanced, and the object remained at rest.
A force greater than 10 N was exerted in a forward direction on the object at exactly five seconds so that the forces were balanced, and the object remained at rest.
Study the image of two people pushing on opposing sides of a dog house at the same time.
Two people pushing on a doghouse. Force vector arrows are marked 25 N upward and 25 N downward; 10 N to the left and 10 N to the right.
Modified by FlipSwitch.
vberla/Shutterstock
Compute the amount of force acting on the doghouse using the vector addition rule.
Responses
0 N, the doghouse remains at rest.
0 N, the doghouse remains at rest.
70 N, the doghouse remains at rest.
70 N, the doghouse remains at rest.
0 N, the doghouse starts moving in one direction and then slows to a stop.
0 N, the doghouse starts moving in one direction and then slows to a stop.
20 N, the doghouse remains at rest.
NEEDS TO BE ONE OF THE ANSWERS SHOWN!!!
70 N, the doghouse remains at rest.
A puck is sliding along a frictionless surface at constant velocity.
Which of the following choices correctly models the forces acting on the puck?
Responses
A puck with one force vector to the right: initial push (person on puck).
Arrows and labels added by FlipSwitch.
Cline, Dusty/Shutterstock
Image with alt text: A puck with one force vector to the right: initial push (person on puck). Arrows and labels added by FlipSwitch. Cline, Dusty/Shutterstock
A puck with three force vectors. Two are equal opposing forces: gravitational (Earth on puck) straight down, and normal force (surface on puck) straight up. An equal force of initial push (person on puck) points to the right.
Arrows and labels added by FlipSwitch.
Cline, Dusty/Shutterstock
Image with alt text: A puck with three force vectors. Two are equal opposing forces: gravitational (Earth on puck) straight down, and normal force (surface on puck) straight up. An equal force of initial push (person on puck) points to the right. Arrows and labels added by FlipSwitch. Cline, Dusty/Shutterstock
A puck with two equal force vectors: gravitational force (Earth on puck) straight down, and initial push (person on puck) to the right.
Arrows and labels added by FlipSwitch.
Cline, Dusty/Shutterstock
Image with alt text: A puck with two equal force vectors: gravitational force (Earth on puck) straight down, and initial push (person on puck) to the right. Arrows and labels added by FlipSwitch. Cline, Dusty/Shutterstock
A puck with two equal opposing forces. Normal force (surface on puck) points straight up, and gravitational force (Earth on puck) points straight down.
Arrows and labels added by FlipSwitch.
Cline, Dusty/Shutterstock
A puck with two equal opposing forces. Normal force (surface on puck) points straight up, and gravitational force (Earth on puck) points straight down.
A puck is sliding along a frictionless surface at constant velocity.
Which of the following choices correctly models the forces acting on the puck?
Responses
A puck with one force vector to the right: initial push (person on puck).
A puck with three force vectors. Two are equal opposing forces: gravitational (Earth on puck) straight down, and normal force (surface on puck) straight up. An equal force of initial push (person on puck) points to the right.
A puck with two equal force vectors: gravitational force (Earth on puck) straight down, and initial push (person on puck) to the right.
A puck with two equal opposing forces. Normal force (surface on puck) points straight up, and gravitational force (Earth on puck) points straight down.
A puck with two equal opposing forces. Normal force (surface on puck) points straight up, and gravitational force (Earth on puck) points straight down.
You push a ball with a net force of 2 N and it accelerates. What happens if you exert 2 N of net force on an object that has 3 times the mass?
Responses
The object will accelerate 1/3 as much because if you apply the same net force but increase the mass, the acceleration will decrease.
The object will accelerate the same amount as before because the mass does not affect the object’s acceleration
The object will accelerate 3 times as much because if you apply the same net force and increase the mass, the acceleration will increase.
The object will not accelerate because now it is too heavy.
The object will accelerate 1/3 as much because if you apply the same net force but increase the mass, the acceleration will decrease.
Study the image.
A couch with two opposing forces. A friction force vector (surface on couch) marked 5 N points to the left. A push force vector (person on couch) marked 20 N points right.
If the couch has a mass of 45 kg, determine its acceleration.
Responses
0.33 m/s2, to the right
3 m/s 2 , to the right
2.2 m/s2, to the right
1.8 m/s2, to the right
To determine the acceleration of the couch, we need to calculate the net force acting on it using the given forces.
The friction force opposing motion is 5 N to the left, and the push force is 20 N to the right.
Net force = 20 N - 5 N
= 15 N (to the right)
Next, we can use Newton's second law of motion:
Net force = mass * acceleration
Rearranging the equation:
Acceleration = Net force / mass
= 15 N / 45 kg
= 1/3 m/s^2 to the right
So, the acceleration of the couch is 0.33 m/s^2 to the right.
An apple is thrown upwards. Which of the following force diagrams best models the forces acting on the apple after it has left the person’s hand and while it’s moving upwards?
Responses
An apple with two opposing forces. A vector showing throw force (person on apple) is equal to a vector showing gravitational force (Earth on apple).
An apple with one force vector showing gravitational force (Earth on apple) pointing down.
An apple with two opposing forces. A vector showing throw force (person on apple) is shorter than a vector showing gravitational force (Earth on apple).
An apple with two opposing forces. A vector showing throw force (person on apple) is longer than a vector showing gravitational force (Earth on apple).
An apple with two opposing forces. A vector showing throw force (person on apple) is shorter than a vector showing gravitational force (Earth on apple).
Study the scenario.
A toy car is pushed across the floor with a force of 4 N to the right. There is 1 N of friction acting on the car to the left.
What is the net force acting on the car?
Responses
5 N
0.25 N
3 N
4 N
To determine the net force acting on the car, we need to calculate the difference between the applied force and the friction force.
The applied force pushing the car to the right is 4 N, and the friction force acting on the car to the left is 1 N.
Net force = Applied force - Friction force
= 4 N - 1 N
= 3 N
Therefore, the net force acting on the car is 3 N.
A 50 kg skydiver is falling downwards and accelerating 6 m/s2 down. What is the net force on the skydiver?
Responses
300 N, up
300 N, down
8.3 N, down
500 N, up
To determine the net force acting on the skydiver, we can use Newton's second law of motion.
The acceleration of the skydiver is given as 6 m/s^2 down, and the mass of the skydiver is 50 kg.
We can use the equation:
Net force = mass * acceleration
Plugging in the values:
Net force = 50 kg * 6 m/s^2
= 300 N
Therefore, the net force on the skydiver is 300 N, downwards.
A child pushes a desk with a force of 15 N to the right. The desk accelerates to the right. Which of the following statements correctly represents Newton’s third law and the interaction between the child and desk?
Responses
The desk did not exert any force on the child.
The desk exerted exactly 15 N of force on the child, but the force is directed to the left.
The desk exerted slightly less than 15 N of force on the child, but the force is directed to the left.
The desk exerted slightly more than 15 N of force on the child, but the force is directed to the left.
According to Newton's third law of motion, for every action, there is an equal and opposite reaction. In this scenario, the child exerts a force of 15 N to the right on the desk. As a result, the desk exerts an equal and opposite force of 15 N on the child, but in the opposite direction.
Therefore, the correct statement is: The desk exerted exactly 15 N of force on the child, but the force is directed to the left.
Study the image
A girl holds an apple with two equal opposing forces: an upward force of hand on apple, and downward force of Earth on apple.
Which of these correctly explains whether this image is an example of Newton’s third law, and why?
Responses
This is an example of Newton’s third law because they are equal in strength, opposite in direction, and acting on one object.
This is not an example of Newton’s third law because although the forces are equal in strength the forces are in the same direction.
This is not an example of Newton’s third law because although they are acting in opposite directions, the forces are unequal in strength.
This is not an example of Newton’s third law because although the forces are equal in strength and opposite in direction, they are acting on one object.
This is an example of Newton’s third law because they are equal in strength, opposite in direction, and acting on one object.
A box is at rest on the floor. Which of the following force diagrams best represents the action-reaction pair of forces between the box and the floor?
Responses
A box with one force: a force vector (floor on box) pointing up.
A box with equal and opposing forces. A force vector (floor on box) points up, and an equal gravitational force vector (Earth on box) points down.
A box with opposing forces. A longer force vector (floor on box) points up, and a shorter force vector (box on floor) points down.
A box with equal and opposing forces. A force vector (floor on box) points up, and an equal force vector (box on floor) points down.
A box with equal and opposing forces. A force vector (floor on box) points up, and an equal force vector (box on floor) points down.
If a bat with a mass of 5 kg and acceleration of 2 m/s2 hits a ball whose mass is 0.5 kg in the forward direction, what is the reaction force of the ball on the bat?
Responses
10 N, backward
0.5 N, upward
0 N, forward
10 N, forward
According to Newton's third law of motion, the reaction force of the ball on the bat will be equal in magnitude but opposite in direction to the force exerted by the bat on the ball.
The force exerted by the bat on the ball can be calculated using Newton's second law of motion:
Force = mass * acceleration
Force = 0.5 kg * 2 m/s^2
Force = 1 N forward
Therefore, the reaction force of the ball on the bat will also be 1 N but in the opposite direction, which is backward.
So, the correct response is: 10 N, backward.
A person is standing on ice. He throws a snowball with a force of 4 N to the right, while the snowball pushes the person with a force of 4 N to the left. What is the net force on the person?
Responses
0 N
8 N
4 N, left
4 N, right
To determine the net force on the person, we need to consider the forces acting on them.
The person exerting a force of 4 N to the right on the snowball and the snowball exerting a force of 4 N to the left on the person form an action-reaction pair of forces according to Newton's third law.
Since these forces are equal in magnitude and opposite in direction, they cancel each other out. Therefore, the net force on the person is 0 N.
So, the correct response is: 0 N.
A box exerts 10,000 Pa of pressure on the ground. If the box weighs 1000 N, how much area is in contact with the ground?
Responses
11,000 m^ 2
10 m^2
10,000,000 m^2
0.1 m^2
Pressure is defined as force divided by area. To determine the area in contact with the ground, we can rearrange the formula:
Area = Force / Pressure
The force exerted by the box is given as 1000 N, and the pressure exerted by the box is given as 10,000 Pa.
Area = 1000 N / 10,000 Pa
= 0.1 m^2
Therefore, the area in contact with the ground is 0.1 m^2.
So, the correct response is: 0.1 m^2.
A liquid is moving through a pipe. If the speed of the liquid decreases, what happens to the pressure within the liquid?
Responses
Only density affects pressure, so pressure stays the same.
The pressure within the liquid decreases.
The pressure within the liquid increases.
The pressure within the liquid becomes zero.
The pressure within the liquid increases.
how did you get that answer?
The answer is based on the Bernoulli's principle, which states that as the speed of a fluid (such as a liquid) decreases, the pressure within the fluid increases.
This principle is derived from the conservation of energy in fluid flow. According to Bernoulli's principle, as the speed of a fluid decreases, the kinetic energy of the fluid decreases. To conserve energy, this decrease in kinetic energy is compensated by an increase in another form of energy, which is the pressure energy.
In simpler terms, when the speed of a liquid decreases, the particles of the liquid are less energetic and collide with each other more frequently. These more frequent collisions result in increased pressure within the liquid.
Therefore, when the speed of the liquid decreases, the pressure within the liquid increases.
A 100 kg boat is floating in water. Half of the boat is submerged under water. What is the weight of the boat?
Responses
50 kg
0 N
980 N
490 N
The weight of an object is the force exerted on it due to gravity.
The weight of the boat can be calculated by multiplying its mass by the acceleration due to gravity (which is approximately 9.8 m/s^2).
Weight = mass x acceleration due to gravity
Given that the mass of the boat is 100 kg, we can calculate the weight:
Weight = 100 kg x 9.8 m/s^2
= 980 N
Two crates are submerged under water. The crates are identical in size, but Crate A is filled with iron and Crate B has only air inside. Which crate has a greater buoyant force acting on it?
Responses
Both crates have the same amount of buoyant force acting on them because they are the same size and displace the same amount of water.
Crate A has a greater buoyant force acting on it because it is filled with iron, making it heavier. Buoyant force depends on the weight of the object.
Crate B has a greater buoyant force acting on it because it is filled with air, so it will float. The object that floats will always have a greater buoyant force acting on it.
There is no way of knowing which object has a greater buoyant force acting on it until we can determine if they float. If both objects float, they have the same amount of buoyant force acting on them.