A car travelling due north at 60 km/hr increased its velocity to 80 m/s due south in 20 seconds draw speed against time graph
acceleration is constant
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To draw the speed against time graph, we need to first convert the given velocities into a consistent unit. Let's convert the initial velocity from km/hr to m/s.
Initial velocity in m/s = 60 km/hr * (1000 m / 1 km) * (1 hr / 3600 s) = 16.67 m/s (approximately)
Now, we have the initial velocity as 16.67 m/s north and the final velocity as 80 m/s south. We know that the change in velocity is the final velocity minus the initial velocity:
Change in velocity = Final velocity - Initial velocity
Change in velocity = -80 m/s - 16.67 m/s
Change in velocity = -96.67 m/s
We also know that the change in velocity is equal to acceleration multiplied by time:
Change in velocity = Acceleration * Time
Since the acceleration is constant, we can rearrange the equation to solve for the acceleration:
Acceleration = Change in velocity / Time
Acceleration = -96.67 m/s / 20 s
Acceleration = -4.83 m/s²
Now, let's plot the speed against time graph:
1. Start by labeling the x-axis as time (in seconds) and the y-axis as speed (in m/s).
2. Choose a suitable scale for both axes. Let's say we use 1 cm for every 1 second on the x-axis and 1 cm for every 10 m/s on the y-axis.
3. Plot the initial velocity of 16.67 m/s as a point above the x-axis on the left side.
4. Since the acceleration is negative, the speed should decrease over time. Draw a sloping line downwards from the initial velocity point to the right.
5. The line should end at a point below the x-axis, representing the final velocity of -80 m/s.
6. Label the starting and ending points with their respective velocities.
The resulting speed against time graph should show a decreasing line from 16.67 m/s to -80 m/s over 20 seconds.