Unit 7 check

Unit 7 check: Oscillations

10 questions from 4 lessons in Unit 7. Answer each one, and if you miss, follow the link back to where it is taught, then try again. Your score counts first tries.

Question 1 · from 7.1 · Decide and justify

A block on a level, frictionless table is joined to a wall by a horizontal ideal spring. It was pulled right and released, and it is now passing through the spot where the spring is relaxed, moving left. Right is positive. What is the net force on the block at that instant?

Which reason supports your answer?

Question 2 · from 7.2 · Sketch the graph

A block slides on a level, frictionless track, attached to an ideal spring with spring constant 40 N/m. The block can be swapped for others of different mass. Sketch the period of the oscillation against the block's mass, from 0 to 1.6 kg. The first point is fixed at 0: a block with almost no mass would have almost no period.

Drag a point up or down, or tap it and use the arrow keys. Only the shape is checked.

Question 3 · from 7.3 · Sketch the graph

A cart on a level track is joined to a horizontal spring, and its wheels roll freely. Right is positive, and $x$ is measured from equilibrium. At $t = 0$ the cart passes through equilibrium moving right. Its amplitude is 10 cm and its period is 1.0 s, so $x = (10 cm) \sin (2 π (1.0 Hz) t)$ . Sketch the cart's position from 0 to 1.0 s, one point every 0.125 s. The first point is fixed at 0.

Drag a point up or down, or tap it and use the arrow keys. The shape is checked, and the graph must pass through the values the question gives.

Setup for question 4

A 0.50 kg glider sits on a level air track, where friction and air resistance are negligible, tied to a horizontal ideal spring whose other end is fixed. A student pulls it 0.25 m from equilibrium and releases it from rest. A motion sensor records the glider's speed as it passes four positions, each measured from equilibrium.

The glider table
Distance from equilibrium (m)	Speed (m/s)
0.25	0.0
0.20	1.2
0.15	1.6
0.00	2.0

Question 4 · from 7.4 · Calculate

Using the glider table, for the 0.50 kg glider released from rest 0.25 m from equilibrium: what is the spring constant of the spring? Give your answer to the nearest 1 N/m.

Your answer N/m

Question 5 · from 7.1 · Sketch the graph

A block on a level, frictionless table is joined to a horizontal ideal spring with spring constant 40 N/m, whose other end is fixed to a wall on the left. A meter stick lies beside it, its numbers increasing to the right, and right is positive. With the spring relaxed, the block rests at the 30 cm mark. Sketch the net force on the block against its position on the meter stick, from 20 cm to 40 cm.

Drag a point up or down, or tap it and use the arrow keys. The shape is checked, and the graph must pass through the values the question gives.

Question 6 · from 7.2 · Multiple choice

A simple pendulum swinging through a small angle has a period of 2.0 s. Its length, pivot to the center of the bob, is made four times as long, and its bob is replaced with one of the same size but twice the mass. What is the new period?

Question 7 · from 7.3 · Decide and justify

A pendulum in a science museum swings through a small angle and takes 4.0 s for each full cycle. A visitor gives it a harder start, so it swings twice as far to each side, still through a small angle. How long does one full cycle take now?

Which reason supports your answer?

Uses the same setup as question 4, above.

Question 8 · from 7.4 · Multiple choice

Using the glider table, how much energy does the spring store when the 0.50 kg glider is 0.15 m from equilibrium?

Question 9 · from 7.1 · Multiple choice

A pendulum's bob is pulled aside and released. Its motion can be modeled as simple harmonic when it is pulled aside a small angle, but not when it is pulled aside a large one. Which statement explains why?

Setup for question 10

A student hangs four simple pendulums from a beam and releases each from rest at a small angle. For each one she records the length from the pivot to the center of the bob, the bob's mass, and the time the pendulum takes for 10 complete oscillations.

The four pendulums
Pendulum	Length (m)	Bob mass (kg)	Time for 10 oscillations (s)
A	0.40	0.050	12.6
B	0.40	0.200	12.5
C	0.90	0.050	18.9
D	1.60	0.200	25.2

Question 10 · from 7.2 · Calculate

Using the pendulum table, what is the frequency of pendulum C? Give your answer to the nearest 0.01 Hz.

Your answer Hz

0 of 10 answered.