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# A person sitting on the ground floor of a building notices through the window, of height 1.5 m, a ball dropped from the roof of the building and crosses the window in 0.1 s. What is the velocity of the ball when it is at the topmost point of the window? (g -10 m/s2)

By BYJU'S Exam Prep

Updated on: September 13th, 2023

**The velocity of the ball when it is at the topmost point of the window is 14.5 meters per second. **Velocity is a physical quantity that describes the rate of change of an object’s displacement with respect to time. In the given question the velocity of the ball will be 14.5m/s when it is at the topmost point of the window.

**Velocity = Δx / Δt**

where:

Δx represents the change in position or displacement of the object,

Δt represents the change in time.

Table of content

## Velocity Of The Ball

Velocity is a vector quantity that represents the rate of change of displacement with respect to time. It includes both the magnitude (speed) and the direction of motion. It is typically expressed in units of meters per second (m/s) or kilometers per hour (km/h).

**For example-**

Let’s consider a car traveling along a straight road. If the car moves 100 meters in 10 seconds towards the east, the velocity of the car can be calculated by dividing the displacement by the time taken:

Displacement = 100 meters (towards the east)

Time = 10 seconds

**Velocity = Displacement / Time**

= 100 meters / 10 seconds

= 10 meters per second (m/s) towards the east

In this example, the velocity of the car is 10 m/s towards the east. The magnitude of the velocity is 10 m/s, indicating the speed of the car, and the direction is towards the east, indicating the car’s motion.

**Solution**

To find the velocity of the ball when it is at the topmost point of the window, we can use the equation of motion:

**v = u + gt**

where:

v is the final velocity,

u is the initial velocity,

g is the acceleration due to gravity (given as 10 m/s^{2}),

and t is the time taken.

In this case, the ball is dropped, so the initial velocity u is 0 m/s.

Given that the height of the window is 1.5 m and the time taken to cross the window is 0.1 s, we can determine the final velocity when the ball reaches the topmost point of the window.

Using the equation:

v = u + gt

Substituting the values:

v = 0 + (10 * 0.1)

v = 14.5 m/s

Therefore, the velocity of the ball when it is at the topmost point of the window is 14.5 m/s.

**Summary**

## A person sitting on the ground floor of a building notices through the window, of height 1.5 m, a ball dropped from the roof of the building and crosses the window in 0.1 s. What is the velocity of the ball when it is at the topmost point of the window? (g -10 m/s^{2})

A person sitting on the ground floor of a building notices through the window, of height 1.5 m, a ball dropped from the roof of the building and crosses the window in 0.1 s. The velocity of the ball when it is at the topmost point of the window (g -10 m/s^{2}) is 14.5 meters per second.

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