Answered

A truck traveling on level ground is subjected to a resisting force (from the brakes and air resistance) of 300 kN for a distance of 10 hm. How much kinetic energy does the truck lose?

A. 1250 MJ
B. -1250 MJ
C. 1250 N
D. 1250 J



Answer :

To determine how much kinetic energy the truck loses, we need to use the concept of work done by the resisting force. The work done by a force is equal to the force multiplied by the distance over which the force is applied. This work done translates into the kinetic energy lost by the truck.

### Step-by-Step Solution

1. Given Values:
- Resisting force [tex]\(F\)[/tex]: 300 kiloNewtons (KN)
- Distance [tex]\(d\)[/tex]: 10 hectometers (hm)

2. Unit Conversions:
- Convert the resisting force from kiloNewtons (KN) to Newtons (N):
[tex]\[ \text{1 kiloNewton (KN)} = 1000 \text{ Newtons (N)} \][/tex]
Therefore,
[tex]\[ F = 300 \text{ KN} \times 1000 \text{ N/KN} = 300,000 \text{ N} \][/tex]

- Convert the distance from hectometers (hm) to meters (m):
[tex]\[ \text{1 hectometer (hm)} = 100 \text{ meters (m)} \][/tex]
Therefore,
[tex]\[ d = 10 \text{ hm} \times 100 \text{ m/hm} = 1000 \text{ m} \][/tex]

3. Calculate the Work Done:
The work done by the resisting force (which corresponds to the kinetic energy lost) is given by the formula:
[tex]\[ W = F \times d \][/tex]
Substituting the values we have:
[tex]\[ W = 300,000 \text{ N} \times 1000 \text{ m} = 300,000,000 \text{ Joules (J)} \][/tex]

### Conclusion:
The kinetic energy lost by the truck is [tex]\(300,000,000\)[/tex] Joules. This is not explicitly listed as one of the options for the multiple-choice question, and there might be a misinterpretation of units or errors in the given choices. Therefore, the provided multiple-choice options do not correctly correspond to the calculated value.

To sum up, despite the mismatch in the options, we have determined that the truck loses [tex]\(300,000,000\)[/tex] Joules of kinetic energy based on the given data.