O present time and speed data on a distance-time graph. KEY WORDS
distance, speed, time
TASK
Sam leaves home at 8 am and drives for half an hour, covering 20 miles. At first his speed increases but, after 25 minutes, it starts to decrease until he stops.
Sam leaves the car and sits for 15 minutes in a coffee shop then walks to a gallery, which is in the opposite direction to his home, for 30 minutes at a constant rate of 4 mph.
He stays at the gallery for an hour then walks back to his car at 3 mph.
He drives home and reaches it at 11.19 am.
Questions
01.​How far does Sam walk from the coffee shop to the gallery?
02. What time is it when he leaves the gallery?
03. How long does it take him to walk back to the car?
04. How long does his drive home take?
05. What is Sam’s average speed on his return car journey?
06. Draw a graph of distance against time to show Sam’s whole journey.

Answer: a charge of -1.0  × 10⁻⁴ c must be placed  at x = 26 m.the sign of the charge will be the same sign as the  -4.0  µc charge.======electricstatic force between two point charges  is given by    where k is coulomb's constant,  8.99×10⁹  n·m²/c², q₁ and q₂ are the point charges, and r is the distance between the two point charges.assign positive to q₁let q₁ =  6.0 µc, q₂ = -4.0  µc, q₀ represent the charge at the origin, and q₃ represent this new charge to place.the charge at the origin q₀ would experience the following force f₀₁ from q₁, with r = 6.0 m (note that 1  µc = 10⁻⁶ c)    the force from q₂    the force from q₃    the net force on the origin charge, q₀, has to be zero for no electrostatic forcehaving an equation where k and q₀ can be divided out of the equation will allow us to solve for q₃    isolating:     a charge of -1.0  × 10⁻⁴ c must be placed  at x = 26 m.the sign of the charge will be the same as the  -4.0  µc charge