A car of mass 2000 kg is moving with a speed of 20
m/s. To stop it brakes are applied. If the retarding
force is 2000 N, the time required to stop the car will
be :
(a) 5 sec (b) 10 sec (c) 15 sec (d) 20 sec.
Share
A car of mass 2000 kg is moving with a speed of 20
m/s. To stop it brakes are applied. If the retarding
force is 2000 N, the time required to stop the car will
be :
(a) 5 sec (b) 10 sec (c) 15 sec (d) 20 sec.
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Answer :
›»› The Time taken to stop the car = 20 sec
Given :
To Calculate :
How To Calculate ?
❒ Here in this question we have to find Time taken to stop the car. So, firstly we need to calculate the Acceleration of car by using the second law of Newton, after that we will find Time taken of car to stop by using the first equation of motion.
Calculation :
‡ From Second law of Newton
⇒ F = ma
⇒ -2000 = 2000 × a
⇒ -2000 = 2000a
⇒ a = -2000/2000
⇒ a = -1 m/s²
【NOTE : -ve sign indicates retardation of car.】
Now, we have three elements that used in formula, Final velocity, Initial velocity and Acceleration of car
And we need to find Time taken by car to stop.
† From first equation of motion
⇛ v = u + at
⇛ 0 = 20 + -1 × t
⇛ 0 - 20 = -t
⇛ -20 = -t
⇛ 20 = t
⇛ t = 20
║Hence, the time taken to stop the car will be 20 seconds.║
Verified answer
Answer:
d) 20sec
Step-by-step explanation:
given,
mass=2000kg
u= 20m/s
v= 0m/s
force= 2000N
force= mass×acceleration
2000= 2000×a
1=a
according to 1st eq. of motion
v=u+at
0=20+(-1)t. (-1 becaue of retardation)
-20=-t
20=t
.......666......