A car drives around a racetrack for 30 seconds. What do you need to know to calculate the instantaneous speed of the car at a given point?

A. The total displacement of the car

B. The time needed to drive 1 lap

C. The slope of the car's position-time graph

D. The average speed of the car

The magnitude of force is 571.2 N.

Explanation:

Given data :-

i) Mass of the box = 84 kg.

ii) Frictionless surface means  friction force is zero.

iii)The force ( F ) which act on box = m*a.  

iv) The time for which the box is in motion ( t ) = 5 seconds.

v) The distance traveled by box ( S ) = 85 meter.

Now to find magnitude of force we have to calculate the value of acceleration.

We know the equation of motion.

S = (u*t )+0.5 (a*t²)

85 = 0 + 0.5 * a *5²     ( u = initial velocity = 0 )

a = 6.8 m²/s.

∴ F = m*a = 84 * 6.8 = 571.2 N