Watchly Safety Review

Measure height with a watch! Cliff jump science

Mark Rober

3:46 · 3.6M views · August 5, 2014

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Minor FlagsReviewed June 2026

4Minor Flags

2No Issues

This video is largely safe and genuinely educational, using cliff jumping as a fun hook to teach real physics concepts like Newton's equations of motion, free fall, and air resistance. The main caveat for parents is that the cliff-jumping activity itself could inspire imitation, though the video's tone is more science-lesson than dare-devil challenge.

Content Breakdown · 6 Categories

Hidden Advertising & Sponsored ContentA little

The description includes a link to 'Active Life Store' for GoPro shots with a referral-style URL, but this is disclosed in the description rather than hidden within the content. The creator also explicitly states the app is free with no ads and no monetization, which is the opposite of hidden promotion.

See evidence (1)

“Special thanks to Active Life Store for the GoPro shots with a referral link in the description.”

Parasocial & Emotional ManipulationNot present

The description includes a standard subscription call-to-action ('PLEASE CONSIDER SUBSCRIBING'), but this is a routine, non-manipulative request with no guilt-tripping or emotional coercion attached.

See evidence (1)

“'PLEASE CONSIDER SUBSCRIBING' in the description — phrased politely without manipulation.”

Engagement Baiting & Manipulative CTAsNot present

The description contains a standard subscription link but uses polite, non-coercive language ('PLEASE CONSIDER SUBSCRIBING') with no superstition CTAs, guilt-tripping, or fake giveaways.

See evidence (1)

“Standard subscription CTA in description: 'PLEASE CONSIDER SUBSCRIBING'”

Low-Quality, Extreme & Stunt ContentA little

While cliff jumping is a stunt-adjacent activity, the video's primary purpose is clearly educational — teaching high school physics using a real-world scenario — rather than shock-value stunt content.

See evidence (1)

“A 48 ft cliff jump is performed, but it serves as the vehicle for a physics lesson rather than as an end in itself.”

Realistic Violence, Threats & WeaponsA little

Cliff jumping is a physically risky activity shown in the video, but it is framed as a voluntary recreational sport with a scientific educational purpose rather than as violence or a threat. No weapons, threats, or depictions of harm are present.

See evidence (1)

“David voluntarily jumps off a 48 ft cliff as part of the demonstration.”

Dangerous Internet ChallengesA little

Cliff jumping is an inherently risky physical activity and is the central subject of the video; however, it is framed as a science demonstration rather than a viral challenge to replicate. The educational framing and the note that '80% of all 100 foot cliff jumps on YouTube aren't [accurately measured]' suggests a cautionary/informational intent rather than promotion of the activity itself.

See evidence (2)

“David jumps off a 48 ft cliff as part of the physics demonstration.”

“The transcript references '100 foot cliff jumps on YouTube,' implying awareness of the risky trend.”

What Parents Need to Know

This video does an impressive job of making high school physics accessible and engaging — kids will learn about free fall equations, gravity, terminal velocity, and even get a reference to an Apollo moon mission experiment. The presenter explains the math clearly and verifies results scientifically, modeling good critical thinking. The concern is that the framing involves cliff jumping, which is an inherently risky activity, and younger or more impulsive viewers might be inspired to try it. There is also a brief mention of a free app the creator made, which is a mild promotional element. The video is best suited for curious tweens and teens who can appreciate the science without fixating on the stunt aspect.

Talk to Your Kids About

1What is the physics equation the video uses to calculate how far something falls, and can you explain in your own words why heavier objects don't fall faster?
2Why do you think the creator verified the math with a measuring string? What does that tell us about how science works?
3The video shows cliff jumping — what are some real risks involved in that activity that the video doesn't fully address?
4Can you think of other ways you could use this falling-time equation in everyday life, without doing anything dangerous?

Measure height with a watch! Cliff jump science

Protected Viewing

What's This Video About?

This is a simple trick using high school physics where you can measure the height of really tall objects like a cliff, using just a stopwatch. Special thanks to Active Life Store for the GoPro shots. You can get one from them here: http://www.bit.ly/1y41QA2 PLEASE CONSIDER SUBSCRIBING: http://tinyurl.com/MarkRober-Sub Here is a link to the FREE app (free as in FREE, as in I don't even have any ads in it or make any money off of it whatsoever) in the app store (sorry, no android at this time): https://itunes.apple.com/us/app/cliff-height-timer/id893030245?mt=8 *************************************************************************** I make videos like this once a month all year long while supplies last: CHECK OUT MY CHANNEL: http://tinyurl.com/MarkRober-YouTube FOLLOW ON TWITTER: https://twitter.com/#!/MarkRober FACEBOOK ME: https://www.facebook.com/MarkRoberYouTube ***MUSIC*** All music created by Qwiet. You should go sub his channel: http://youtube.com/qwietmusic Twitter: http://twitter.com/qwiet Facebook: http://facebook.com/qwiet

Frequently Asked Questions

What age is this video appropriate for?

We recommend this video for ages 10 and up. The physics content is best appreciated by kids who have some exposure to basic math and science, and older viewers are less likely to fixate on the cliff-jumping stunt rather than the educational lesson.

Could this video inspire dangerous cliff-jumping behavior in kids?

There is a mild risk that younger or more impulsive viewers could be drawn to the cliff-jumping aspect rather than the science. Parents of younger children or risk-prone kids may want to watch alongside them and emphasize that cliff jumping carries serious real-world dangers not fully discussed in the video.

Is there any advertising or sponsored content in this video?

The creator briefly promotes a free app they built called 'Cliff Height Timer,' which is a minor self-promotional element. It is not a paid sponsorship and is relevant to the video's topic, but parents should be aware the app mention is present.

What does my child actually learn from watching this video?

Kids learn how to apply Newton's equation of motion to calculate the height of objects using only a stopwatch, and they're introduced to concepts like free fall, gravity, air resistance, and terminal velocity. The video also references a real NASA Apollo 15 experiment, giving historical and scientific context.

Is the science in this video accurate?

Yes, the physics presented is accurate and well-explained. The creator correctly applies the free-fall equation, acknowledges the limitations of air resistance, and even verifies results empirically — modeling good scientific practice for young viewers.

Is there any inappropriate language or content in this video?

There is no profanity, sexual content, or inappropriate language in this video. The content is clean and focused on science, making it suitable for school-age children when watched with some parental context about the risks of the stunts shown.