Acceleration

Acceleration is the rate at which an object changes its velocity by increasing its speed, decreasing its speed, or changing its direction.



For instance, if you push a toy car across a surface, you can measure the distance it covers in a given time. By increasing the force of the push, you can increase the car’s acceleration, causing it to cover a greater distance in the same amount of time.

Acceleration is a vector quantity, meaning that it has both magnitude and direction and is represented as a change in velocity over time.

The formula for acceleration:

acceleration = (final velocity – initial velocity)/time.

The direction of the acceleration depends on the direction of the change in velocity.

Questions:

  1. Define acceleration.
  2. What is the difference between speed and velocity?
  3. A car travels at a velocity of 50 m/s for 2 hours, then increases its velocity to 75 m/s. What is the car’s acceleration?
  4. An object starts from rest and reaches a velocity of 20 m/s in 5 seconds. What is the object’s acceleration?
  5. If an object’s initial velocity is 10 m/s and its final velocity is 25 m/s, and it takes 4 seconds to reach that final velocity, what is its acceleration?
  6. What is the unit of acceleration in the International System of Units (SI)?
  7. A ball is thrown upward with an initial velocity of 30 m/s. How long does it take for the ball to reach its maximum height? What is its acceleration at that point?
  8. An object is moving with a constant velocity of 10 m/s. Is the object experiencing acceleration? Explain why or why not.
  9. If an object is moving with a negative acceleration, what does that mean?
  10. A rocket is launched from the ground and experiences an acceleration of 50 m/s2. How fast will the rocket be traveling after 10 seconds?

Answer Key:

  1. Acceleration is the rate at which an object changes its velocity.
  2. Speed is a scalar quantity that refers to how fast an object is moving, while velocity is a vector quantity that takes into account the object’s direction of motion.
  3. The car’s acceleration is 12.5 m/s 2

4. The object’s acceleration is 4 m/s2

5. The object’s acceleration is 3.75 m/s 2

6. The unit of acceleration in SI is meters per second squared (m/s 2).

7. The ball reaches its maximum height in 3 seconds, and its acceleration at that point is -9.8 m/s 2.
At the top point the final velocity is zero and acceleration = acceleration due gravity = -9.8 m/s 2

8. No, the object is not experiencing acceleration because its velocity is constant.
9. A negative acceleration means that the object is slowing down.
10. The rocket will be traveling at a velocity of 500 m/s after 10 seconds

Handouts

7. AccelerationDownload
7. Acceleration (printing version)Download
7. Acceleration (answers)Download
8. AccelerationDownload
8. Acceleration (printing version)Download
8.. Acceleration (answers)Download
9. AccelerationDownload
9.Acceleration (printing version)Download
9. Acceleration (answers)Download

Notes

  1. The acceleration is defined as the rate at which an object’s velocity changes over the time taken. It is a vector quantity, meaning it has both magnitude and direction, representing how fast an object speeds up, slows down, or changes direction. The SI unit for acceleration is meters per second squared (m/s2) ↩

  2. Velocity: the speed of an object in a given direction – it tells how fast something moves and which way it’s going. Find out more about Speed and Velocity ↩

  3. Speed: how fast an object moves – the distance travelled per unit time, without considering direction. ↩

  4. Distance: the total length of a path travelled by an object, regardless of direction. ↩

  5. Force (push): a push applied to an object that can change its motion, shape, or direction. ↩

  6. Vector quantity: a physical quantity that has both magnitude (size) and direction. ↩

  7. Magnitude: the size or amount of a quantity, without cosidering direction. ↩

  8. Direction: the way an object moves or points, such as north, east, up, or left. ↩

  9. Change in velocity: the difference between an object’s final and initial velocity, caused by speeding up, slowing down, or changing direction. ↩

  10. Final velocity: the velocity of an object at the end of a motion or time period. ↩

  11. Initial velocity: the velocity of an object at the start of a motion or time period. ↩

  12. Starts from rest: an object begins motion with zero velocity (initial velocity (u) = 0m/s ↩

  13. International System of Units (SI): the standard system of measurment used worldwide in science, based on agreed base units like metres, kilogram, an srcond. ↩

  14. Constant velocity: motion where an object’s speed and direction stay the same, so its velocity does not change. ↩

  15. Scalar quantity: a physical quantity that has magnitude (size) only and no direction. ↩

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