Understanding Motion and Velocity

What is the main difference between speed and velocity?

• Speed is always greater than velocity.

• The main difference is that speed is scalar (magnitude only), while velocity is vector (magnitude and direction).

• Speed includes direction while velocity does not.

• Velocity can only be measured in kilometers per hour.

Answer explanation

The correct choice highlights that speed is a scalar quantity, meaning it has only magnitude, while velocity is a vector quantity, which includes both magnitude and direction. This distinction is fundamental in physics.

If a car travels 100 meters in 5 seconds, what is its speed?

• 20 meters per second

• 15 meters per second

• 25 meters per second

• 30 meters per second

Answer explanation

To find the speed, divide the distance by the time. Speed = Distance / Time = 100 meters / 5 seconds = 20 meters per second. Therefore, the correct answer is 20 meters per second.

Define acceleration in the context of motion.

• Acceleration is the force applied to an object.

• Acceleration is the rate of change of velocity over time.

• Acceleration is the speed of an object at a given moment.

• Acceleration is the distance traveled over time.

Answer explanation

Acceleration is defined as the rate of change of velocity over time, meaning it measures how quickly an object's speed or direction changes. This makes the second answer choice the correct one.

How do you calculate acceleration if a car's speed changes from 20 m/s to 50 m/s in 5 seconds?

• 6 m/s²

• 8 m/s²

• 10 m/s²

• 4 m/s²

Answer explanation

To calculate acceleration, use the formula: a = (final speed - initial speed) / time. Here, a = (50 m/s - 20 m/s) / 5 s = 30 m/s / 5 s = 6 m/s². Thus, the correct answer is 6 m/s².

What is the formula for calculating distance when speed and time are known?

• Distance = Time / Speed

• Distance = Speed + Time

• Distance = Speed - Time

• Distance = Speed × Time

Answer explanation

The correct formula for calculating distance when speed and time are known is Distance = Speed × Time. This means that to find the distance traveled, you multiply the speed by the time spent traveling.

Explain the concept of displacement and how it differs from distance.

• Displacement is the shortest distance from the initial to the final position with direction, while distance is the total path length traveled without direction.

• Displacement measures the time taken to travel between two points.

• Displacement is the total distance traveled in any direction.

• Distance is always shorter than displacement.

Answer explanation

Displacement is defined as the shortest straight-line distance from the starting point to the endpoint, including direction. In contrast, distance refers to the total length of the path traveled, regardless of direction.

If a person walks 3 km east and then 4 km west, what is their displacement?

• 4 km east

• 1 km east

• 1 km west

• 3 km west

Answer explanation

The person walks 3 km east and then 4 km west. The net movement is 1 km west (4 km west - 3 km east = 1 km west). Thus, the displacement is 1 km west.

What does a velocity-time graph represent?

• A velocity-time graph represents acceleration as a constant value.

• A velocity-time graph shows how velocity changes over time.

• A velocity-time graph shows the distance traveled over time.

• A velocity-time graph indicates the speed of an object at a specific moment.

Answer explanation

A velocity-time graph illustrates how an object's velocity varies over time, making it clear how speed changes, which is essential for understanding motion.

How can you determine acceleration from a velocity-time graph?

• Acceleration is the total distance divided by time.

• Acceleration is the area under the curve of the graph.

• Acceleration is determined by the y-intercept of the graph.

• Acceleration is determined by the slope of the velocity-time graph.

Answer explanation

Acceleration is determined by the slope of the velocity-time graph. The slope represents the change in velocity over time, which is the definition of acceleration.

If an object is accelerating, how does it affect its speed over time?

• The object's speed decreases over time.

• The object's speed remains constant over time.

• The object's speed fluctuates randomly over time.

• The object's speed increases over time.

Answer explanation

When an object is accelerating, it means there is a net force acting on it, causing its speed to increase over time. Therefore, the correct choice is that the object's speed increases over time.