4. What force can stop a 1400 kg truck accelerating at 7.5 m/s/s?

10.5 kN

Explanation:

Force is a product of mass and acceleration, therefore, expressed as am=F

Where a is acceleration of an object, m is the mass and F is rhe force exerted.

Given m as 1400 kg and a as 7.5 m/s2 then force will be

F=1400*7.5=10500 N

Converted to kN

We know that 1 kN=1000 N

Therefore, to convert 10500 N to kN, we divide the above by 1000 hence 10500/1000=10.5 kN

Therefore, the force is equivalent to 10.5 kN