Answer:
magnitude of the frictional torque is 0.11 Nm
Explanation:
Moment of inertia I = 0.33 kg⋅m2
Initial angular velocity w° = 0.69 rev/s = 2 x 3.142 x 0.69 = 4.34 rad/s
Final angular velocity w = 0 (since it stops)
Time t = 13 secs
Using w = w° + §t
Where § is angular acceleration
O = 4.34 + 13§
§ = -4.34/13 = -0.33 rad/s2
The negative sign implies it's a negative acceleration.
Frictional torque that brought it to rest must be equal to the original torque.
Torqu = I x §
T = 0.33 x 0.33 = 0.11 Nm
for acceleration we can define that rate of change in velocity is know as acceleration
So whenever velocity of train is changing with time we can say train is accelerating
Now here if initially train is standstill then after some time its speed is 5 m/s
so here the train is accelerated first time
Then on straight path its speed changed from 5 m/s to 10 m/s so here train gets accelerated second time
After this train chugged around a curve with same speed 10 m/s
SO here since train is moving in curve so here its direction of velocity is continuously changing and this type of acceleration is known as centripetal acceleration
SO this is accelerated Third time
Then its speed decreases and it comes to speed of 5 m/s from 10 m/s
So here it is acceleration of train for Fourth time
Then finally train comes to stop so again its speed changed from 5 m/s to 0
so this is acceleration of train Fifth time
So total train will accelerate 5 times in whole path
Answer: B. A gravitational field
Explanation:
Surrounding earth is gravitational field. Gravitational field is a region of space were gravitational force can be felt and gravitational force is the gravitational pull on the surface of the earth. The presence of this gravity is what allow us to be able to walk freely without falling. It also make us jump up and be able to land back on the ground. Assuming there are no force of gravity in the surface of the earth, there won't be any possibility of landing back on the ground after jumping.
Explanation:
there is no relationship between small mass and the bigger mass, but it can be related with the acceleration. Since Force is constant, acceleration is inversely proportional to the mass. Greater the mass, lesser is the acceleration and vise versa
Average speed = (total distance) / (time to cover the distance)
We know:
Average speed = 65 km/hr
Total distance = 1,000 km
Time to cover it = (Driving Time) + 4 hours.
so we can write:
65 km/hr = (1,000 km) / (Driving Time + 4hr)
(I'm going to start calling the driving time 'DT'.
Notice that DT is a number with the units of 'hours'.)
Multiply each side by (DT + 4hr)
(65 km/hr) (DT + 4hr) = 1,000 km
Eliminate parentheses on the left side:
(65·DT km + 260 km) = 1,000 km
Subtract 260km from each side:
65·DT km = 740 km
Divide each side by 65 :
DT = 11.38 hours .
DT (Driving Time) is the time you spent actually driving.
You had to cover the complete 1,000 km in that time.
So while you were driving, you had to do it at a speed of
1,000 km / 11.38 hrs = 87.8 km/hr .
__________________________________________
As long as we're already totally bored by this question,
let's work on it some more, and check my answer:
... Driving for 11.38 hours at a speed of 87.8 km/hr, you cover
(11.38 hr) x (87.8 km/hr) = 999.164 km (close enough to 1,000) .
So far, so good. The distance is taken care of.
With the 4-hour stop, the total trip takes 4 more hours = 15.38 hours.
So the average speed is
(1,000 km) / (15.38 hr) = 65.02 km/hr
Close enough to 65 km/hr. yay !
