Kinematics and Forces on a Single Object

The diagram above represents the motion of an object that travels to the right in a straight line path. Each dot represents the position of the object at 0.1 s intervals; black dots are labeled with the times at which the object was at that position. Which of the following best estimates the instantaneous speed of the object at time = 1.5 seconds?

• .2 meters/1.5 seconds

• .2 meters/.1 seconds

• 4.5 meters/1.5 seconds

• 4.5 meters/.1 seconds

A person walking along a straight line moves such that her velocity as a function of time can be represented by the graph above. At what time does the person have the same position as she had at time t = 0?

• At t = 5 s

• During the interval 5 s < t < 8 s

• At t = 8 s

• During the interval t > 8 s

A toy car is initially at rest and travels a straight-line distance of 16 meters in T seconds. Starting at time t = 0, the car has a uniform acceleration of 2 m/s² until it reaches a speed of 4 m/s. The car then continues with this velocity time t = T.

What is the value of T?

• 4 s

• 5 s

• 8 s

• 12 s

Tags

NGSS.HS-PS2-1

A student performs an experiment to determine whether an object released from rest truly exhibits free-fall motion. The student takes data of distance d that the object has fallen at various times t after the object is released. If the object does exhibit free-fall motion, which of these graphs will be a line?

• d vs. t

• d vs. t²

• d² vs. t

• d² vs. t²

A car starting from rest accelerates for T seconds with constant acceleration a, traveling a distance D and reaching a speed v. After another T seconds have passed, the car is now a distance 3D from its initial position. What did the car do during the second T-second interval of time?

• The car continued accelerating forward with constant acceleration a.

• The car ceased to accelerate and continued forward with constant velocity v.

• The car slowed down with a backward acceleration –a until it stopped.

• None of these things can account for the car’s final position.

Tags

NGSS.HS-PS2-1

A student conducts an investigation into the motion of a car that accelerates from rest on a straight, level roadway. A driver operating the car causes the car to speed up from rest at time t = 0 and the student makes measurements of the distance traveled and the speed of the car every second.

What experimental evidence would support the conclusion that the car’s acceleration is uniform? Select two answers.

• All objects released from rest at the same time fall together.

• The distance fallen is proportional to the square of the falling time.

• A graph of velocity vs. time is linear.

• Objects speed up as they free-fall.

Tags

NGSS.HS-PS2-1

Apollo 13 is a 1995 movie about a mission to the Moon that experiences serious problems. In the movie, an astronaut says, “We just put Sir Isaac Newton in the driver’s seat.” This line, a reference to Newton’s First Law, is spoken just after

• the rocket begins firing its engines and lifts off from the launch pad.

• the spacecraft begins firing its engines on its way back to Earth from the Moon.

• the spacecraft enters Earth’s atmosphere and air resistance begins to slow its descent.

• the spacecraft has finished firing its engines and has spent all of its fuel.

An aircraft flying to the right has a constant horizontal speed of 200 m/s has four forces acting on it shown above left. When the aircraft passes through the cloud at point S (shown above right), the force of thrust has the same magnitude as the force of drag, and the force of lift balances the force of weight. If this condition continues, which path shown above right will the plane follow?

• A

• B

• C

• D

• E

Tags

NGSS.HS-PS2-1

A skydiver falling through the air opens her parachute. The skydiver and parachute together have a weight W. At a specific instant after the parachute opens, the force of air resistance on the parachute is 1.4W. What is the acceleration of the parachute-and-skydiver system at this instant?

• 14 m/s² downward

• 4 m/s² downward

• 4 m/s² upward

• 14 m/s² upward

Tags

NGSS.HS-PS2-1

A student hypothesizes that a certain elastic cord exerts a constant force even as the cord contracts to its natural length. To test this hypothesis, the student attaches the cord to a cart and stretches the cord a significant distance. The student releases the cart and measures the increase in speed Δv of the cart during an interval of time Δt. If the student performs multiple trials in which the mass M of the cart is varied, which of the following graphs would yield a line if the cord’s force were constant?

• M vs. (Δv/Δt)

• M vs. (Δt/Δv)

• M² vs. (Δv/Δt)

• M2 vs. (Δt/Δv)

Tags

NGSS.HS-PS2-1