Read the first worked example with the solution open so the structure is clear.
Try the practice problems before revealing each solution.
Use the related concepts and background knowledge badges if you feel stuck.
What to Focus On
Core idea:Acceleration starts by naming what changes, over what time interval, and whether direction matters.
Common stuck point:Students often know a formula related to acceleration but skip the recognition step: Am I describing motion over time with position, distance, direction, speed, velocity, or acceleration clearly separated? That leads to a correct-looking substitution attached to the wrong physical model.
Sense of Study hint:Ask: Am I describing motion over time with position, distance, direction, speed, velocity, or acceleration clearly separated?
Worked Examples
Example 1
easy
A car accelerates from 10 m/s to 30 m/s in 5 s. What is the acceleration?
Answer
a=4 m/s2
First step
1
Use the acceleration formula: a=ΔtΔv.
Full solution
2
Substitute the initial and final velocities: a=530−10.
3
a=520=4 m/s2
Acceleration is the rate of change of velocity. A positive acceleration means the object is speeding up in the positive direction.
Example 2
medium
A car traveling at 25 m/s brakes and comes to rest in 5 s. What is the deceleration, and how far does it travel while braking?
Example 3
medium
A car accelerates uniformly from rest to 20m/s over 40m. (a) Find the acceleration. (b) Find the time it takes.
Example 4
medium
A roller coaster speeds up uniformly from 5m/s to 25m/s over 40m. Find the acceleration.
Example 5
hard
A car accelerates from rest at a1=3m/s2 for 4s, then at a2=2m/s2 for 6s. Find its final velocity and total distance traveled.
Example 6
hard
Two sprinters start side-by-side. Sprinter A accelerates from rest at 2m/s2; sprinter B starts 1.5s later from rest at 3m/s2. When does B catch A?
Example 7
challenge
A drag racer accelerates uniformly from rest and covers 400m in 8.0s. Find (a) the acceleration and (b) the top speed.
Practice Problems
Try these problems on your own first, then open the solution to compare your method.
Example 1
medium
An object starts from rest and accelerates at 3 m/s2 for 8 s. What is the final velocity and distance traveled?
Example 2
medium
A cyclist accelerates uniformly from 4 m/s to 12 m/s over 8 seconds. (a) What is the acceleration? (b) How far does the cyclist travel during this time?
Example 3
easy
A car speeds from 0 to 20 m/s in 4 s. Find its acceleration.
Example 4
easy
A car slows from 30 m/s to 10 m/s in 5 s. Find its acceleration.
Example 5
easy
An object's velocity is constant. What is its acceleration?
Example 6
easy
A bike accelerates at 2 m/s2 from rest. Its velocity after 6 s?
Example 7
easy
Acceleration is −9.8 m/s2 for 2 s on an object initially at 5 m/s up. Find the velocity change.
Example 8
easy
What are the units of acceleration?
Example 9
easy
An object goes from 4 m/s to 4 m/s over 3 s (constant). Acceleration?
Example 10
easy
A car accelerates at 3 m/s2. How long to gain 15 m/s?
Example 11
medium
A car at 8 m/s accelerates at 2 m/s2 for 5 s. Find its final velocity.Velocity addition: 8 m/s + 10 m/s gained over 5 s = final velocity
Example 12
medium
Starting from rest at a=4 m/s2, how far does an object travel in 3 s?
Example 13
medium
A car decelerates from 20 m/s to rest over 50 m. Find the (constant) acceleration.
Example 14
medium
An object moving at −6 m/s has acceleration −2 m/s2. Is it speeding up or slowing down?
Example 15
medium
A train reaches 40 m/s from 10 m/s with acceleration 3 m/s2. How long did it take?
Example 16
medium
A car accelerates uniformly from 5 m/s to 25 m/s in 4 s. Find the distance covered.
Example 17
challenge
A car accelerates from rest at 2 m/s2 for 5 s, then holds speed for 5 s. Total distance?
Example 18
challenge
Two cars start together; A accelerates at 2 m/s2 from rest, B moves at constant 10 m/s. When does A catch B?
Example 19
challenge
A ball thrown up at 19.6 m/s (g=9.8 m/s2). Using acceleration reasoning, find the time to reach the highest point.
Example 20
medium
A car accelerates at 2.5 m/s2 from 10 m/s. Find its speed after 4 s.
Example 21
medium
An object decelerates uniformly from 24 m/s to 0 in 6 s. Find the acceleration.
Example 22
medium
From rest at a=6 m/s2, find the distance after 2 s.
Example 23
easy
A jogger speeds up from 2m/s to 5m/s in 6s. Find the acceleration.
Example 24
easy
A skateboarder slows from 8m/s to 2m/s in 3s. Find the acceleration.
Example 25
easy
A car cruises at a steady 30m/s down a straight highway. What is its acceleration?
Example 26
easy
Starting from rest at a=2.5m/s2, find the velocity after 4s.
Example 27
easy
An object's acceleration is constant at −3m/s2 while moving at +12m/s. Find the velocity 2 s later.Opposing acceleration reduces velocity from 12 m/s to 6 m/s after 2 s
Example 28
easy
An object near Earth's surface is in free fall. What is its acceleration?
Example 29
medium
A bike at 10m/s accelerates at 1.5m/s2 for 6s. Find the distance traveled.
Example 30
medium
A truck decelerates at −1.2m/s2 from 24m/s. How long until it stops, and how far does it travel?
Example 31
medium
An object's velocity changes from −4m/s to +6m/s in 5s. Find its acceleration.
Example 32
medium
A ball is dropped from rest. Using g=9.8m/s2, find its speed after 1.5s.
Example 33
medium
A car going +8m/s has acceleration −2m/s2. After 3s what is its velocity, and is it now moving forward or backward?
Example 34
medium
A car accelerates at 3m/s2 from rest, covers some distance, and reaches 30m/s. Find the distance.
Example 35
medium
A toy car accelerates at 0.5m/s2 from rest. How long until it has covered 4m?
Example 36
medium
On a velocity-time graph, a straight line rises from 4m/s at t=0 to 14m/s at t=5s. Find the acceleration and the distance covered.
Example 37
hard
A car at 20m/s brakes with constant deceleration and stops in 50m. Find the deceleration and the stopping time.
Example 38
hard
An elevator accelerates upward at 1.5m/s2. A passenger of mass 70kg stands on a bathroom scale. What reading does the scale show? (Use g=9.8m/s2.)
Example 39
hard
A ball thrown vertically upward leaves the hand at 24m/s. Using g=9.8m/s2, find the maximum height reached.
Example 40
challenge
An object moves in a circle of radius 2m at a constant speed of 4m/s. Find its acceleration.