Probably one of my favourite @pascoscientific tools the ball launcher on the smartcart. It's real science getting the students to predict whether the ball will fall into the catcher when it is moving and working out why.
In a world of digital screens and virtual simulations, there’s still something powerful—and fun—about real-world experiments that make physics concepts come alive. One such example is the PASCO Smart Cart with a Ball Launcher, a compact but mighty piece of equipment for demonstrating fundamental mechanics. It’s particularly good at visualising Newton’s Laws of Motion, projectile motion, and relative motion—all with satisfying thunks as the ball flies and lands back in place.
In this blog post, we’ll look at a classic demo and then explore what happens when we add a twist: acceleration.
1. The Classic: Constant Velocity and Newton’s First Law
The standard demonstration begins with the Smart Cart moving down a track at constant velocity. When the built-in launcher fires, the ball travels vertically upward in the cart’s frame—but in the lab frame (i.e., to an observer on the ground), the ball follows a parabolic trajectory.
Because the cart keeps moving at the same horizontal speed as the ball had at launch, the ball falls neatly back into the launcher cup.
This shows Newton’s First Law in action: the ball retains its horizontal motion unless acted upon by a force (and there isn’t one horizontally, assuming no air resistance). The same logic explains why, on a moving train, a ball tossed straight up appears to land back in your hand—if the train isn’t accelerating!
2. The Twist: What Happens When the Cart is Accelerating?
Now let’s place the cart on a slightly inclined ramp so that it accelerates as it moves. What happens if the launcher fires now?
In this case, the ball still carries the horizontal velocity of the cart at the moment of launch. But here’s the key: the cart doesn’t continue at that same velocity—it speeds up due to gravity. That means by the time the ball comes back down, the cart has moved ahead, and the ball lands behind the cup.
This simple observation dramatically shows the breakdown of Newton's First Law under non-inertial (accelerating) frames and reinforces the principle that in the absence of external forces, an object continues in uniform motion.
3. Visual Analysis: Using PASCO Capstone and Motion Vectors
As seen in the second image (Capstone screenshot), using PASCO Capstone software and video tracking tools, you can overlay:
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The projectile path of the ball (red dots),
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The velocity vectors (purple, green, orange) at different points,
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A reference vertical measuring stick or grid (red and green alternating bars).
This lets students visualise how velocity components change and how horizontal acceleration affects the landing point.
4. Further Experiments with the Smart Cart & Launcher
Here are some creative extensions:
A. Collision & Launch
Let one cart move at speed and collide with a stationary cart. Trigger the launcher at the moment of impact using a photogate or acceleration threshold. Students can explore conservation of momentum and energy.
B. Relative Motion Challenge
Set up two carts on adjacent tracks. One cart launches a ball while both move at different speeds. Challenge students to calculate whether the ball can still land in the cup on the other cart, and adjust for success!
C. Air Track Equivalent
Simulate frictionless conditions by placing the cart and launching on an air puck setup. Compare trajectories in low-friction environments versus on a ramp.
D. Angular Launch
Angle the launcher slightly off vertical (Two cameras required) and observe projectile motion in two dimensions. This introduces trigonometry and initial velocity components.
E. Varying Mass & Launch Speed
Use different projectiles or vary the launch tension (if adjustable) and track the impact on projectile height and range. This builds in energy considerations and allows for equations of motion to be tested.
Conclusion
The PASCO Smart Cart with Launcher is a powerful tool for bringing Newton’s Laws to life. Simple experiments—like watching a ball fall back into a cup or miss it due to acceleration—are memorable and impactful for learners. Add in Capstone software’s vector tracking, and you’ve got a modern physics lab in motion.
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