Neglecting the effect of air resistance how long a stones takes to dropped off a 125m high building stand’s on the ground, take g = 10m/s2?

A. 3 Sec
B. 4 Sec
C. 18 Sec
D. 5 Sec

Answer

Correct Answer: D. 5 Sec

Detail about MCQs

When neglecting the effect of air resistance, you can use the following kinematic equation to calculate the time it takes for a stone to fall from a certain height:
Distance=12×Acceleration×Time2Distance=21×Acceleration×Time2
In this case, the distance is 125 meters (height of the building), and the acceleration due to gravity (g) is given as 10 m/s^2. We need to find the time (t). Rearrange the equation to solve for time:
125 m=12×10 m/s2×Time2125m=21×10m/s2×Time2
Now, solve for Time:
Time2=2×125 m10 m/s2=25 s2Time2=10m/s22×125m=25s2
Taking the square root of both sides:
Time=25 s2=5 sTime=25s2=5s

A body is moving with momentum of 100kg m/s. what is the magnitude of force required to stop body in 25 sec?

A. 4 N
B. 25 N
C. 100 N
D. 1500 N

Answer

Correct Answer: A. 4 N

Detail about MCQs

To calculate the magnitude of force required to stop a body with a certain momentum, you can use the formula for force:
Force=Change in MomentumTimeForce=TimeChange in Momentum
In this case, the initial momentum of the body is 100 kg m/s, and you want to stop it in 25 seconds, so the change in momentum is equal to the initial momentum because you want to bring it to rest:
Change in Momentum = Initial Momentum = 100 kg m/s
Time = 25 seconds
Now, plug these values into the formula:
Force=100 kg m/s25 s=4 NForce=25s100kg m/s=4N
So, the magnitude of force required to stop the body in 25 seconds is 4 N. Therefore, the correct answer is A. 4 N.

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