The mean may be calculated by summing the values of the refractive index and dividing the sum by the number of experiments. This is:
Mean = (1.45 + 1.56 + 1.54 + 1.44 + 1.54 + 1.53)/6
Mean = 1.51
The mean absolute error is the sum of the absolute values of errors divided by the number of trials:
MAE = (|1.45-1.51|+|1.56-1.51|+|1.54-1.51|+|1.44-1.51|+|1.54-1.51|+|1.53-1.51|)/6
MAE = 0.043
The fractional error is the MAE divided by the actual value:
Fractional error = 0.043 / 1.51
Fractional error = 43/1510
The percentage error is the fractional error multiplied by 100:
Percentage error = 2.85%
C: if it senses unequal currents
Answer:
the length of the simple pendulum is 0.25 m.
Explanation:
Given;
mass of the air-track glider, m = 0.25 kg
spring constant, k = 9.75 N/m
let the length of the simple pendulum = L
let the frequency of the air-track glider which is equal to frequency of simple pendulum = F
The oscillation frequency of air-track glider is calculated as;

The frequency of the simple pendulum is given as;

Thus, the length of the simple pendulum is 0.25 m.
Answer:
He needs 1.53 seconds to stop the car.
Explanation:
Let the mass of the car is 1500 kg
Speed of the car, v = 20.5 m/s
He will not push the car with a force greater than, 
The impulse delivered to the object is given by the change in momentum as :

So, he needs 1.53 seconds to stop the car. Hence, this is the required solution.