1. a car travelling at 20km/hr speeds up to 80km/hr in 8 seconds . What is its acceleration?
2. A body starts to slide over a horizontal surface with an intial velocity of 0.5m/s . Due to friction,its velocity decreases at the rate of 0.05 m/s. How much time will it take for the body to stop?
Answers
Answer:
- U= 20 km/h = 20*5/18= 50/9 m/s
v= 60 km/h = 60*5/18= 50/3 m/s
t= 6 s
a= v-u/t
= 50/3-50/9÷6
= 100/9÷6
= 100/9×1/6
= 50/27 m/s^2
2. U=0.5 m/s
a=-0.05 m/s²
v=0
By first equation of motion, we have:
v=u+at
0=0.5-0.05t
0-0.5=-0.05t
-0.5=-0.05t
0.5/0.05=t
50/5=t
10 s=t
Hope It helps you
Answer:
Explanation:
Mathematical we use Harmonic Mean to calculate the average speed, but I assume the concept of Harmonic Mean doesn't exist, let's calculate it with pure logic.
The total distance covered by car is 80 KM(40+40).
Now their are two cases:
Case 1) Distance covered 40km, speed 80km/h. Now we all know speed=Distance/ time
So Time taken is 0.5 hour.
Case 2) Now again distance covered is 40 km but speed is 40Km/h
So time taken is 1hrs
Now total distance traveled is 80KM. Total time taken is 1.5 hrs(0.5+1)
Average speed =Total Distance/Total Time
Average Speed = 80/1.5
Which is equal to 53.33km/h
You can use physics to calculate how far an object will slide down an inclined surface, such as a ramp. For example, say you and your friends are pushing a refrigerator up a ramp onto a moving van, when suddenly your combined strength gives out and the refrigerator begins to plummet back down the 3.0-meter ramp.