#  Newton's Second Law, Gravity and Friction Forces 

 



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### Scantling and Ball

\[M | t | ★★★\]  
Ball rolling down tilted trough in oscillatory fashion yields acceleration. Also known as Galileo's Inclined Plane).   
  
\[[In-Depth Description](/presentations/scantling-and-ball)\]

### Uniform Acceleration

\[L | t+ | —\]   
Glider acceleration by an inclined air track or by a falling weight/string attachment; large ballbearing rolling on PASCO track (with strings).   
  
\[[In-Depth Description](/presentations/uniform-acceleration)\]

### Atwood's Machine

\[M | t+ | —\]  
Combinations of weights suspended over pulley to show that asymmetry causes acceleration.   
  
\[[In-Depth Description](/presentations/atwoods-machine)\]

### Double Atwood's Machine

\[M | t+ | —\]  
Prediction of motion of mass in a more complex wheel, axle, and pulley assembly.   
  
\[[In-Depth Description](/presentations/double-atwoods-machine)\]

### Brachistochrone

\[M | t | —\] Straight and cycloidal inclined paths, with the ball on the cycloidal path always beating the straight one to the bottom.

\[[In-Depth Description](/presentations/brachistochrone)\]

### Ball and Strobe

\[L | t++ | —\]  
Ball and Strobe A ball is dropped 5 meters and photographed under stroboscopic illumination.

### Newton's Apple

\[L | t++ | ★★★★\]  
Apple electronically released from platform; fall time given by special circuit and digital display.  
  
\[[In-Depth Description](/presentations/newtons-apple)\]

### Friction Blocks

\[M | t | ★\]  
Selection of blocks that slide down a variable-angle inclined plane to demonstrate the various aspects of friction.

\[[In-Depth Description](/presentations/friction-blocks)\]

### Locked Brakes

\[M | t | ★★★\]   
The difference between static and kinetic friction can cause the car to skid when braking.  
  
\[[In-Depth Description](/presentations/locked-brakes)\]

### Rope Friction around Pole

\[M | t+ | — \]  
The tension force in a rope grows exponentially with the number of turns the rope makes around a pole.

\[[In-Depth Description](/presentations/rope-friction-around-pole)\]

### Resistance to Free Fall

\[M | t+ | —\]  
Ping Pong balls are dropped in air and SF6 for comparison

### Nutty Free Fall

\[L | t+ | —\]  
Large nuts linked by threads at different distances (d, 4d, 9d, 16d, 25d, etc.) dropped from platform; sound of landing gives equal time intervals.

### Falling Faster than 'g'

\[M | t | ★★\]  
Allow a stick to rotate under the force of gravity and the free end will accelerate at a rate greater than *g*. Relation between angular acceleration and linear acceleration seems to give free-fall paradox.  
  
\[[In-Depth Description](/presentations/falling-faster-g)\]

### Feather and Dime

\[L | t+ | ★★\]  
Falling in an evacuated tube at the same rate.   
  
\[[In-Depth Description](/presentations/feather-and-dime)\]

### Drop-n-Catch

\[L | t+ | —\]  
Ball drops from mast of PASCO cart; its motion can be considered relative to the moving cart or the track frame of reference.   
  
\[[In-Depth Description](/presentations/drop-n-catch)\]

### Shoot-n-Drop

\[S | t+ | —\]  
Ball shot horizontally, one dropped vertically; both hit the ground at the same time.  
  
\[[In-Depth Description](/presentations/shoot-n-drop)\]

### Shoot-n-Catch

\[L | t++ | —\]  
Ball shot up from PASCO cart is caught by same; a puzzler to ponder if track is tilted and cart accelerates down (or decelerates up).   
  
\[[In-Depth Description](/presentations/shoot-n-catch)\]

### Shoot the Monkey

\[L | t++ | ★★★★\]  
Monkey released from platform is shot by simultaneously fired cannon.   
  
\[[In-Depth Description](/presentations/shoot-monkey)\]

### Reversible (Kater's) Pendulum

\[M | t | ★★\]  
A physical pendulum with two adjustable knife edges for an accurate determination of "g".  
  
\[[In-Depth Description](/presentations/reversible-katers-pendulum)\]

### Potential Well

\[M | t | ★\]  
Orbital motion simulated by ball rolling on wooden potential well.   
  
\[[In-Depth Description](/presentations/potential-well)\]

### Cavendish Experiment

\[L | t++ | ★★★★\]  
Calculation of gravitational constant, with accompanying apparatus model.  
  
\[[In-Depth Description](/presentations/cavendish-experiment)\]

### Contact Us

**Mailing Address**: Lecture Demonstration Services, Science Center, Rm B-08A, 1 Oxford Street, Cambridge, MA 02138  
**Campus Location**: Science Center B-08A | **Tel**: (617) 495-5824 | **Email**: scidemos-at-fas.harvard.edu