AP Physics Dynamics

An object of mass 10  kg is released from rest above the surface of a planet such that the object’s speed as a function of time is shown by the graph above. The force due to gravity exerted on the object is most nearly

• 3.5 N

• 7 N

• 35 N

• 70 N

Tags

NGSS.HS-PS2-1

Two bricks are stacked on a floor. A student draws the force diagram for brick 2, as shown above. The forces are an upward normal force, a downward force exerted by brick 1, and a downward gravitational force. How many of the forces, if any, in the force diagram are contact forces caused by microscopic interactions?

• Zero

• Only one

• Only two

• All three

A cart with an unknown mass is at rest on one side of a track. A student must find the mass of the cart by using Newton’s second law. The student attaches a force probe to the cart and pulls it while keeping the force constant. A motion detector rests on the opposite end of the track to record the acceleration of the cart as it is pulled. The student uses the measured force and acceleration values and determines that the cart’s mass is 0.4 kg. When placed on a balance, the cart’s mass is found to be 0.5 kg. Which of the following could explain the difference in mass?

• The track was not level and was tilted slightly downward.

• The student did not pull the cart with a force parallel to the track.

• The wheels contain bearings that were rough and caused a significant amount of friction.

• The motion sensor setting was incorrect. The student set it up so that motion away from the sensor would be the negative direction.

Tags

NGSS.HS-PS2-1

A tennis ball is thrown against a vertical concrete wall that is fixed to the ground. The ball bounces off the wall. How does the force exerted by the ball on the wall compare with the force exerted by the wall on the ball?

• The force exerted by the ball is greater.

• The forces exerted by the ball and the wall have the same magnitude.

• The force exerted by the ball is smaller.

• The relative magnitudes of the forces cannot be determined without knowing how long the ball and the wall are in contact.

Tags

NGSS.HS-PS2-1

The diagram above represents the forces exerted on a box that a child is holding. F_N represents the force applied by the child’s hand, and F_g represents the weight of the box. The child begins to raise the box with increasing speed. Which of the following claims is correct about force F_h that is exerted by the box on the child’s hand as the box is being raised?

• F_h=F_N, where F_N does not change as the child raises the box.

• F_h=F_N, where F_N is larger as the box is being raised than when it was being held.

• F_h=F_g, where F_g does not change as the child raises the box.

• F_h=F_g, where F_g is larger as the box is being raised than when it was being held.

Tags

NGSS.HS-PS2-1

Students work together during an experiment about Newton’s laws. The students use a setup that consists of a cart of known mass connected to one end of a string that is looped over a pulley of negligible friction, with its other end connected to a hanging mass. The cart is initially at rest on a horizontal surface and rolls without slipping when released. The inertia of the cart's wheels is negligible. Students have access to common laboratory equipment to make measurements of components of the system.

The students double the mass that hangs from the string. They also replace the original cart with a new cart that has double the mass. By doubling both masses, how will the tension in the string and the acceleration of the cart change?

• The tension and the acceleration will double.

• The tension will double, but the acceleration will stay the same.

• The tension will stay the same, but the acceleration will double.

• The tension and the acceleration will stay the same.

Tags

NGSS.HS-PS2-1

A student uses both hands to push a door such that it moves and swings open after the force has been applied. The student then makes the following claim: “I can use both of my hands to apply a constant force on my body so that my body falls backward.” Which of the following statements correctly justifies the student's claim?

• The claim is correct because the situation is the same as if another person’s hands applied a force on the student.

• The claim is correct because the student’s hands will exert a net force on the student’s body.

• The claim is not correct because the student’s hands cannot exert a force on the student’s body.

• The claim is not correct because the student’s body will exert a force of equal magnitude back on the student’s hands as a result of Newton’s third law of motion.

Tags

NGSS.HS-PS2-1

Blocks A and B, of masses m and 2m, respectively, are connected by a light string and pulled across a surface of negligible friction with a constant force F₁, as shown above. The acceleration of the blocks is a. The force of the string pulling block B forward has magnitude F₂. Which of the following claims correctly describes the relationship between the magnitude of the forces acting on the blocks?

• F₁ is equal to F₂.

• F₁ is greater than F₂.

• F₂ is equal to 3ma.

• F₂ is greater than 3ma.

Tags

NGSS.HS-PS2-1

The force diagram above shows a box accelerating to the right on a horizontal surface of negligible friction. The tension T is exerted at an angle of 30° above the horizontal. If μ is the coefficient of kinetic friction between the box and the surface, which of the following is a correct mathematical equation derived by applying Newton’s second law to the box?

• 
• 
• 
• 

Tags

NGSS.HS-PS2-1

A block is pulled along a surface of negligible friction by a spring scale that exerts a force F on the block. The mass of the block is 4kg, and the spring scale reads 10N. Which of the following free-body diagrams can be used to show the magnitude and direction of all the forces exerted on the block as it is pulled along the surface?

• 
• 
• 
• 

Tags

NGSS.HS-PS2-1