12. A car is travelling at 20 km/h, it speeds upto 60 km/h in 6 seconds. What is its acceleration?
Answers
Answer:
1.85 m/s^2
Explanation:
According to the given question,
u = initial velocity = 20 km/h = 20×1000/3600 = 5.55 m/s
v = final velocity = 60 km/h = 60×1000/3600 = 16.67 m/s
t = time = 6 sec
a = acceleration
And we are asked to find the acceleration of the car.
We know,
- v = u+at
Putting the values we get,
- 16.67 = 5.55+6a
- 6a = 16.67-5.55
- 6a = 11.11
- a = 11.11/6
- a = 1.85 m/s^2
Thus acceleration of the body is 1.85 m/s^2 from the given data of u, v and t.
ANSWER!
Welcome to the science of equations of motions.
To solve such numericals it important to check the units in which the digits are given to us. If necessary then convert the units to S. I system or C.G.S system and vice-versa.
So as we can see the units of speed are as follows:
Speed = 20km/h and 60km/h
(the above values of speed is also the initial velocity (u) and final velocity (v) of the car, respectively.
The unit of speed is derived from the units of distance and time respectively.
The unit of time in the above numerical is in seconds.
Time = t = 6 sec.
Convert the units of speed from S. I system to C. G. S system i.e initial velocity and final velocity.
So,
initial velocity = u = 20km/h
1 km = 1000m
1hr = 3600 seconds
Initial velocity(u)= 20×1000/3600
initial velocity (u) = 5.55 m/s
final velocity (v) = 60km/h
final velocity (v) = 60×1000/3600
final velocity (v) = 16.67 m/s
time = 6 seconds
To find:
acceleration (a)
Solution:
Using the first equation of motion,
v = u + at
Substitute the values,
16.67= 5.55 + a×6
16.67 = 5.55 + 6a
Switch the values from RHS to LHS
16.67 - 5.55 = 6a
11.12 = 6a
a = 11.12/6
a = 1.85 m/s²
Hence, the acceleration of the car is 1.85m/s².