Calculate how will the force between two charged spheres be changed if the distance between the spheres' centers is reduced to half its original value?

Why is it important always to use horizontal bars in unit fractions when performing unit conversions?

What are the similarities & differences between a thermistor and a light dependent resistor in physics?

In which situation is the acceleration of a car negative? question 5 options: a)the velocity of a car was 75 km/hr over 4 hours. b)the velocity of a car reduced from 50 km/hr over one minute. c)the velocity of a car increased from 40 km.h to 75 km/h over 15 minutes. d)the velocity of a car was 45 km/hr at 2: 00pm and at 4: 00pm its velocity was 85 km/ht.