DCP #2 Review - Pt. 1

Front

The diagram shows a duck swimming in a stream in the opposite direction the stream is flowing. The duck pushes against the way, so the water pushes the duck forward with 20 N of force. The water also exerts 15 N of resistive force against the duck.

Is the duck going to continue moving in its current direction or move in the opposite direction?

Back

The duck will continue moving in its current direction because the resistive force is less than the duck's force.

Answer explanation

The duck will continue moving in its current direction due to inertia, as there is no force acting on it to change its motion. Thus, the correct choice is that the duck will continue moving in its current direction.

Front

A mother and daughter push their hands together and then push apart while ice skating. Immediately after they push away from each other, what is the motion of each person?

Who has a greater acceleration?

Back

Both move backward, but the daughter moves with a greater acceleration because her mass is smaller than her mom's.

Answer explanation

When the mother and daughter push away, the mother moves backward due to her greater mass, while the daughter moves forward with a greater acceleration because of Newton's third law, which states that for every action, there is an equal and opposite reaction.

Front

The diagrams show forces acting on a toy car as it moves to the right. Which diagram shows the toy car that will most likely accelerate to the right based on these conditions?

Back

F - because the force pulling to the car to the right is greater than the force pulling from the left.

Answer explanation

Diagram F shows a net force acting to the right, indicating that the toy car will accelerate in that direction. The other diagrams either show balanced forces or forces acting in the opposite direction.

Front

Newton's 3rd Law of Action Reaction PAIR Forces:

Action Force: The basketball pushes down on the gym floor with equal force.

Reaction: ?

Back

Reaction: The gym floor pushes up on the basketball with equal force.

Answer explanation

The correct statement describes Newton's third law: for every action, there is an equal and opposite reaction. The gym floor exerts an upward force on the ball equal to the downward force the ball applies to the floor.

Front

Based on the data table, which cart has the lowest acceleration?

Hint:

*A = F/mass

*Subtract the Frictional Force from the Applied Force to know the Net Force.

Back

X - (15-10)/10 = 0.5

Answer explanation

Cart X has the lowest acceleration as indicated by the data table, which shows its acceleration value is less than that of carts W, Y, and Z.

Front

Why would Cart X have the lowest acceleration in comparison to the rest of the carts?

Back

The cart will have the lowest acceleration if it has a larger mass and has the least difference between its applied force and friction.

Answer explanation

A larger mass results in lower acceleration according to Newton's second law. If the difference between applied force and friction is minimal, the net force is reduced, leading to the lowest acceleration for Cart X.

Front

A small sphere enters one end of a plastic tube with enough speed to come out the other end. Which diagram shows where the sphere will go first when it leaves the tube?

Back

Diagram D because of inertia. There is no unbalanced force would change it's direction when it leaves the tube.

Answer explanation

When the sphere exits the tube, it will continue in the direction it was moving. Diagram D shows the sphere moving straight ahead, which is the correct path based on its initial velocity.

Front

Which description best identifies the action-reaction pair between the bird and the fence post?

Back

Action: The bird pushes down on the fence post
Reaction: The fence post pushes up on the bird

Answer explanation

The correct action-reaction pair is: Action: The force of the bird on the fence post, Reaction: The force of the fence post on the bird. This follows Newton's third law, where every action has an equal and opposite reaction.

Front

When a coin is tossed in the air, it travels upward, gradually slows down, momentarily reaches zero speed, then moves back downward with increasing speed.

What force changes it's velocity (speed/direction)?

Back

The force of gravity causes the coin to change its velocity (speed/direction)

Answer explanation

The force of gravity acts on the coin throughout its motion, causing it to decelerate as it rises, stop momentarily at the peak, and then accelerate downward, changing its velocity.

Front

According to Newton’s first law (An object changes motion when an unbalanced force acts on it), what happens to the steel ball just after the box stops? Does the ball continue to move or does it stop with the box?

Back

Because of inertia, the ball continues rolling forward at the same speed until an unbalanced force (the wall of the box) causes it stop moving.

Answer explanation

According to Newton's first law, an object in motion stays in motion at the same speed unless acted upon by an external force. Since the box stops but no force acts on the ball, it continues rolling forward at the same speed due to inertia.