Question

11) A body moving along a straight
line at 20 m/s decelerates at the
rate of 4 m/s. After 2 seconds its
speed will be equal to​

Answer 1

Solution :

⏭ Given:

• Initial velocity of car = 20mps
• Deceleration rate = 4m/s$^2$
• Time interval = 2s

⏭ To Find:

• Final velocity of body

⏭ Formula:

✏ As per first equation of kinematics relation between initial velocity, final velocity, acceleration and time is given by...

$\bigstar \: \boxed{ \red{ \tt{ \large{v = u + ( - a)t}}}} \: \bigstar$

✏ Negative sign shows deceleration.

⏭ Terms indication:

• u denotes initial velocity
• v denotes final velocity
• a denotes acceleration
• t denotes time

⏭ Calculation:

$\circ \sf \: v = u - at \\ \\ \circ \sf \: v = 20 - (4 \times 2) \\ \\ \circ \sf \: v = 20 - 8 \\ \\ \circ \: \boxed{ \tt{ \large{ \purple{v = 12 \: mps}}}}$

⏭ Additional information:

• Velocity is a vector quantity.
• SI unit of velocity is m/s