Even Physics Textbooks Tend to Get Friction Slightly Wrong

Even Physics Textbooks Tend to Get Friction Slightly Wrong

Let's consider a very basic physics problem involving pushing a block with a frictional force . Suppose I have a very low-friction cart with a constant-strength force pushing on it (in this case, it has a fan mounted on top).

The Biomechanical Perfection of Simone Biles in Flight

The Biomechanical Perfection of Simone Biles in Flight

And then, pow pow, Biles is in the air, a möbius loop of motion 10 feet off the ground at the apex, more than a second in the air, twisting around her head-to-toe axis three times and flipping over her side-to-side axis twice before, bang!

Self-Parking Garages, Robovans, and More Car News This Week

Self-Parking Garages, Robovans, and More Car News This Week

Speaking of electrics, we watched Ford’s prototype battery-powered Ford F-150 haul a train, saw Cruise delay its plans to launch a robo-taxi service in San Francisco, and inspected financials from Tesla showing that while deliveries are up, so are losses.

Quantum Darwinism Could Explain What Makes Reality Real

Quantum Darwinism Could Explain What Makes Reality Real

One of the most remarkable ideas in this theoretical framework is that the definite properties of objects that we associate with classical physics—position and speed, say—are selected from a menu of quantum possibilities in a process loosely analogous to natural selection in evolution: The properties that survive are in some sense the “fittest.” As in natural selection, the survivors are those that make the most copies of themselves.

How Elite Tennis Players Crank Out Serves at 150 MPH

How Elite Tennis Players Crank Out Serves at 150 MPH

A former tennis pro himself, Kovacs works with some of the best players on Earth to help them wring as much power as possible from their serves.

The Awesome Bowling Robot Is Surely Fake. Here's How to Tell

The Awesome Bowling Robot Is Surely Fake. Here's How to Tell

Motion of the Spinning Arm. I already have an estimate for the launch speed of the ball from the time it takes to get down the lane.

How to Shoot Stellar Slow-Motion Video on Your Phone

How to Shoot Stellar Slow-Motion Video on Your Phone

Many phones let you record HD video (1080p) at even higher frame rates: 240 fps slo-mo has become pretty common among premium devices, like the Pixel 3, the OnePlus 7 Pro, and the Galaxy S9.

SpaceX Recovered Its First Rocket Fairing. Let’s Crunch the Numbers!

SpaceX Recovered Its First Rocket Fairing. Let’s Crunch the Numbers!

So, if the boat can travel at 30 mph and it has 41 minutes to get to the rendezvous spot for the fairing, how big of a target area do you need.

The Physics of the Millennium Falcon's Jump to Hyperspace

The Physics of the Millennium Falcon's Jump to Hyperspace

To estimate the acceleration, we can look at the angular size of the back of the Falcon as it moves away. All I need to do is measure the position of the sides of the Falcon and use that to calculate the angular size in each frame of the video during the jump to hyperspace.

How to Solve a Rubik's Cube in 5 Seconds—or Less

How to Solve a Rubik's Cube in 5 Seconds—or Less

Last month, at a speedcubing competition in Brisbane, he set a new world record of 5.69 seconds in the Average of 5 event, wherein contestants each solve five cubes that have been scrambled according to computer-generated instructions.

Apple Is Finally Fixing the Keyboards on MacBook Pros

Apple Is Finally Fixing the Keyboards on MacBook Pros

More than a year and a half after some MacBook owners began vociferously complaining about broken MacBook keyboards, Apple is making what it says is a material change in the keyboards in its high-end MacBook Pro laptops.

Lilium's 36-Motor Flying Taxi Takes Off for the First Time

Lilium's 36-Motor Flying Taxi Takes Off for the First Time

The aircraft would pitch the fan assemblies vertically for takeoff, then transition them 90 degrees for horizontal flight, with the aerodynamic wing and fuselage providing most of the lift at cruising speed.

The Best Speed Climbers Dash up Walls With a Time-Saving Move

The Best Speed Climbers Dash up Walls With a Time-Saving Move

It's essentially the Fosbury flop of speed climbing: For the athletes like Fishman who can pull it off, the Reza can shave tenths of a second from their overall times.

5 of the Best Demos of Projectile Motion and Its Quirks

5 of the Best Demos of Projectile Motion and Its Quirks

Both balls start with the same vertical position and the same vertical velocity (zero m/s) so that they have the same motion in the vertical direction and hit the ground at the same time. The water will shoot out horizontally, just like projectile motion.

The Physics of the Doppler Effect, Represented as Tiny Balls

The Physics of the Doppler Effect, Represented as Tiny Balls

Notice how the balls look "bunched up" on the left side of the sound source but spread out on the right side? Here is a plot of the apparent ball frequency for a source moving at 4 m/s with the ball sound speed of 10 m/s.

The Physics of Building Jumps in The Matrix

The Physics of Building Jumps in The Matrix

If I assume he jumps like a normal human with an upward speed of 3 m/s (this would give a 0.6 second hang time), then the gravitational field would be 1.4 N/kg.

Safety-Obsessed Volvo Goes After Distracted, Speedy Drivers

Safety-Obsessed Volvo Goes After Distracted, Speedy Drivers

After announcing a few weeks ago that it will limit the top speed of all its new cars to 112 mph, Volvo will roll out efforts to eliminate impaired driving, keep young drivers in check, and help its competitors benefit from its years of safety research.

A New Wave of Brainy Bikes Do Everything but Ride Themselves

A New Wave of Brainy Bikes Do Everything but Ride Themselves

That follows on the release, last summer, of Fox Racing Shox’s Live Valve, an electronically controlled suspension system that reacts almost instantly to terrain, and the year before, an automatic gear-shifting mode for Shimano’s STEPS e-bike drivetrain.

Calculate How Fast Quicksilver Is Moving in X-Men Apocalypse

Calculate How Fast Quicksilver Is Moving in X-Men Apocalypse

If I know the time this takes and the total distance, I can calculate the average speed as: Rhett Allain That seems straightforward, but I need to point out that this is the average speed.

Audi Cars Tell You How Fast to Go to Catch All Green Lights

Audi Cars Tell You How Fast to Go to Catch All Green Lights

The Green Light Optimization Speed Advisory system is an expansion of Audi’s vehicle-to-infrastructure communication system: Since 2016, it has offered “time-to-green,” which tells the driver sitting at a red light how long they have to look at their phone before it’s time to go.

Russian Hackers Go From Foothold to Full-On Breach in 19 Minutes

Russian Hackers Go From Foothold to Full-On Breach in 19 Minutes

Analyzing more than 30,000 attempted breaches in 2018 the company says it detected across its customer base, Crowdstrike measured the time from hackers' initial moment of intrusion to when they began to expand their access, jumping to other machines or escalating their privileges within a victim network to gain more visibility and control.

Launch an 80,000-Pound Sled off an Aircraft Carrier? Sure!

Launch an 80,000-Pound Sled off an Aircraft Carrier? Sure!

Since the sled is launched horizontally, the starting vertical velocity is zero meters per second. If I had the height of the flight deck, I could use that and the vertical motion to find the time it takes to hit the water.

Sprint Sues AT&T, Proving ‘5G’ Is Still Meaningless

Sprint Sues AT&T, Proving ‘5G’ Is Still Meaningless

The four largest US mobile carriers have largely settled on the LTE, or "Long Term Evolution" standard for their 4G networks.

10 Years Later, Retrace the 'Miracle on the Hudson' Flight

10 Years Later, Retrace the 'Miracle on the Hudson' Flight

10 Years Later, Retrace the 'Miracle on the Hudson' Flight The Airbus jet was just 2,800 feet up and nowhere near its cruising speed when the engines failed, giving pilots Chesley “Sully” Sullenberger and Jeffrey Skiles just a few minutes to find a safe path to the ground.

The Heir to the V-22 Osprey Flies Through a Year of Testing

The Heir to the V-22 Osprey Flies Through a Year of Testing

The two aircraft don’t share any hardware, but they both use swiveling rotors to switch between flying vertically (to take off and land like a helicopter) and horizontally (to cruise like a plane).That connection has concentrated extra attention on the aircraft’s testing phase, and Bell and partner Lockheed Martin, which is in charge of the avionics and weapons systems, have done just about everything they can to smooth out its adolescence.“The whole idea from the beginning has been to find simple solutions for complex designs,” says Jeff Josselyn, manager of V-280 flight maintenance at Bell’s Arlington, Texas, headquarters.

Rotating Detonation Engines Could Propel Hypersonic Flight

Rotating Detonation Engines Could Propel Hypersonic Flight

Rotating Detonation Engines Could Propel Hypersonic Flight You know in movies, how the heroes are running away from an explosion, then get knocked forward by the shockwave?

Use a Slo-Mo Video to Calculate How Fast Glass Shatters

Use a Slo-Mo Video to Calculate How Fast Glass Shatters

Oh, don't forget to change the frame rate in the video.Here is the plot of the position of the leading edge of the crack as a function of time.Rhett AllainI should point out that I converted the distance to meters instead of feet because I'm not a barbarian (but if you are a barbarian, I'm OK with that).

How to Ride a Bike at 168 MPH

How to Ride a Bike at 168 MPH

“That was like a match to gasoline,” says Mueller-Korenek.This weekend’s attempt comes two years after Mueller-Korenek hit 147.7 mph on her bike at Bonneville, setting the women’s speed record (by virtue of being the first woman to try it).

Climate shocks an 'early warning call' to act on rising hunger, UN says

Climate shocks an 'early warning call' to act on rising hunger, UN says

Climate shocks such as droughts, floods and variable rainfall, are already causing a rise in hunger, a situation UN economists describe as an “early warning call” for action on food insecurity.

This Week in the Future of Cars: What Happened at Tesla, Uber, and Chevy this week

This Week in the Future of Cars: What Happened at Tesla, Uber, and Chevy this week

Alex chats with Waymo veteran and Aurora CEO Chris Urmson on why the startup will be smarter about machine learning than its competition, and how close its tech is to being able to do everything a human can.One year into his role as CEO of Uber, Dara Khosrowshahi reflects—and introduces a new suite of safety features.One Montana startup is using Doppler lidar—the same tech that cops use to catch speeding drivers—to create colorful images that just might give cars a better (and safer) sense of what is gong on around them.As part of a string of electrifying announcement from major automakers, Mercedes-Benz unveils its first fully electric SUV.

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