PRACTICE COLLECTION / 36 PROBLEMS
Motion & forces
Read motion, choose a frame and draw the forces. Each problem includes progressive hints, guided reasoning and a question to test the idea again. Problems marked “Free sample” are complete for everyone; membership opens the rest.
LEARN BEFORE YOU PRACTISE
Build the reasoning first.
Velocity and acceleration
Read motion as changing position—and changing velocity
4 worked examples · 6 checks →Motion with constant acceleration
Derive the equations, choose an interval, and know when a calculated answer stops describing the motion.
4 worked examples · 7 checks →From interactions to equations
Learn to choose a body, draw its forces, and explain a change of motion before calculating it.
4 worked examples · 7 checks →Static friction: find what is needed
Replace “friction equals μN” with a method that tests whether surfaces can remain at rest relative to each other.
4 worked examples · 8 checks →Projectile motion and moving observers
Use one clock for both axes, then simplify encounters by comparing relative positions and velocities.
8 worked examples · 8 checks →Connected bodies, sliding friction and accelerating frames
Build force equations from the system, the contact state and the geometry of each connection.
9 worked examples · 8 checks →Forces that turn a moving object
Derive inward acceleration, resolve real forces and test the limits of circular motion.
6 worked examples · 6 checks →CONCEPTS IN THIS COLLECTION
PRACTISE AT YOUR PACE
Problems in this collection
36 problems · Showing 12
Motion & forces
What happens at the highest point?
The ball stops rising. It doesn’t stop moving.
Compare casesMotion & forces
Can velocity be zero while acceleration is not?
At the instant the cart reverses direction, what is its acceleration?
Compare casesMotion & forces
Does friction always equal μN?
What friction force acts on the case?
Compare casesMotion & forces
Why isn’t the average speed simply five?
What is the average speed for the whole trip?
Compare casesMotion & forces
Read the end of the velocity line
Connect an initial velocity with the velocity change produced by steady acceleration.
Apply a principleMotion & forces
When do the two carts meet?
Opposite motions shrink the gap at the sum of their speed magnitudes.
Apply a principleMotion & forces
A return trip separates displacement from distance
What is the average velocity from 0 s to 5 s?
Read graphs & measurementsMotion & forces
Find the edge of the static-friction interval
What is the minimum upward F that can hold the block at rest?
Find a missing quantityMotion & forces
Terminal balance also predicts the earlier acceleration
What is its downward acceleration when its speed is half its terminal speed?
Connect conceptsMotion & forces
Balance in an accelerating frame
Find the string tension.
Connect conceptsMotion & forces
How far does the cart travel before stopping?
Find the stopping distance.
Find a missing quantityMotion & forces
Cross the river, then measure the drift.
How far downstream does the swimmer land?
Connect concepts12 of 36 shown