Midterm Physics Review

Multiple Choice

Find the value of x in the triangle shown here.

• $$x=\sqrt[]{53}$$

• $$x=\sqrt[]{45}$$

• $$x=\sqrt[]{14}$$

• $$x=9$$

Fill in the Blanks

A red ball moves horizontally in a 30 m long tube. The position of the ball in meters over time is shown here.

What is the displacement of the red ball between 12 s and 24 s?

Fill in the Blanks

As shown in the figure here, Luis rushes 40 m toward his truck. He notices he forgot his shoes and returns back to his house. His total travel time is 60 s.

What is Luis’s average velocity over the 60 s period?

Multiple Choice

A hungry rabbit sprints toward a vegetable garden in a straight line. Its motion is shown on the graph of horizontal position x vs. time t.

What is the average velocity of the rabbit between the times t = 2 s and t=12 s?

• $$0.30\ \frac{m}{s}$$

• $$0.10\ \frac{m}{s}$$

• $$-0.10\ \frac{m}{s}$$

• $$-0.75\ \frac{m}{s}$$

Multiple Choice

Sarah drives east at 30 m/s then slows to a stop at the red light. A graph of her acceleration over time is shown here, where eastward is the positive acceleration direction.

Which graph shows her velocity over time?

Answer using a coordinate system where east is positive.

Multiple Choice

A driver traveling at 100 km/h notices the speed limit changes to 50 km/h. The driver takes 0.9 s to slow down to 50 km/h with constant acceleration. We want to know how many meters the driver travels while slowing down.

Which kinematic formula would be most useful to solve for the target unknown?

Assume the initial direction of travel is the positive direction.

• $$\Delta x=\left(\frac{v+v_0}{2}\right)\cdot t$$

• $$v^2=v_0^2+2\cdot a\cdot\Delta x$$

• $$\Delta x=v_0\cdot t+\frac{1}{2}a\cdot t^2$$

• $$v=v_0+a\cdot t$$

Fill in the Blanks

It took a squirrel 0.50 s to run 5.0 m leftward to a nearby tree while maintaining a constant acceleration. The squirrel was running 15 m/s leftward when it reached the tree.

What was the squirrel's initial velocity?

Give the correct sign for your answer, using a coordinate system where rightward is positive.

Round the answer to two significant digits.

Multiple Choice

Irene drops a clay ball at time t=0. The ball stops when it hits the ground.

Which of the following graphs best shows the velocity v of the clay ball from when it is dropped until it hits the ground?

Assume upward is the positive direction.

Multiple Choice

A block of cheese B hangs from the ceiling by rope 1. A wheel of cheese W hangs from the block of cheese by rope 2.

What is the correct free body diagram for the block of cheese B?

Multiple Choice

An airplane flies with constant velocity.

Which claim about the forces acting on the airplane must be true?

• There is a net force on the airplane.

• There is no net force on the airplane.

• There are no forces on the airplane.

• There is not enough information.

Multiple Choice

A person rides in an elevator.

What is the equal and opposite force for the force of the elevator floor pushing up on the person as described by Newton's third law?

• Person’s force of gravity pulls up on the elevator

• Earth’s force of gravity pulls down on the person

• Person’s force of gravity pulls up on the Earth

• Person pushes down on the floor

Multiple Choice

Problem

A cannonball is fired upwards and to the right from the edge of a cliff, at an angle of 18° degree with the horizontal, at time t=0. We can ignore air resistance.

Which graph best describes the cannonball's vertical acceleration over time?

Assume the origin of the coordinate system to be the cliff edge.

Fill in the Blanks

A skateboarder rolls horizontally off the top of a staircase at a speed of 14.5 m/s and lands at bottom of the stairs. The staircase has a horizontal length of 8.00 m. We can ignore air resistance.

What is the skater's vertical displacement during the jump?

Round your answer to three significant digits

Multiple Choice

A ball is kicked at an angle with negligible air resistance as seen below. Point P is at the ball’s maximum height.

Which direction is the ball’s vertical velocity at point P (the peak of the trajectory)?

• Up

• Down

• Not enough information

• No vertical velocity

Fill in the Blanks

Imagine two pairs of books.

In the first pair, two books of mass m₁ and m₂ are separated by the distance r, resulting in a gravitational force F₁

In the second pair, two books of mass 2m₁ and 4m₂ are separated by the distance 2r, resulting in a gravitational force of F₂.

The relationship between these two forces can be written as F₂ = nF₁

In the expression F₂ = nF₁ what is the value of n?

Multiple Choice

Which of Kepler's Laws states that a planet moves in its ellipse so that the line between it and the Sun placed at a focus sweeps out equal areas in equal times.

• 1st Law

• 2nd Law

• 3rd Law

• This is not one of Kepler's Laws

Multiple Choice

A 25 N force F is applied to a bar that can pivot around its end as shown here.

The force is perpendicular to the bar and is r = 0.75m away from the end.

What is the torque on the bar?

Answer using a coordinate system where counterclockwise is positive.

• - 25 Nm

• 25 Nm

• - 19 Nm

• 19 Nm

Multiple Choice

A uniform meter stick with equally spaced tick marks has a fulcrum at its center, and a downward force F is applied to the meter stick at the position shown. A downward force of F/3 is then applied to the meter stick.

At which position should the downward force F/3 be applied to keep the meter stick in equilibrium?

• Position $$x_1$$

• Position $$x_2$$

• Position $$x_3$$

• Position $$x_4$$

Fill in the Blanks

A 0.20 kg mass is oscillating at a small angle from a light string with a period of 0.78 s.

What is the length of the pendulum?

Round answer to two significant digits.