Can you please help me with the following questions? please.

1. how much work do you do on a 25-kg backpack when you walk a horizontal distance of 100 m?
-I got 2,500 J

4. if you friend pushes a lawnmower four times as far as you do while exerting only half the force, which one of you does more work? how much more? ( I don't understand this question)

7.why does one get tired when pushing against a stationary wall when no work is done on the wall?
-I got because the wall is pushing back with the same equal amount of force.

9. which requires more work streching a strong spring a certain distance or streching a weak spring the same distace? Why?

Sure, I'd be happy to help you with these questions!

1. To calculate the work done on a backpack, you can use the formula: work = force × distance. However, to find the force exerted on the backpack, you'll need to consider the effect of gravity. The force exerted on an object due to gravity is given by the formula: force = mass × acceleration due to gravity. In this case, the mass of the backpack is 25 kg, and the acceleration due to gravity is approximately 9.8 m/s^2. So, the force exerted on the backpack is (25 kg × 9.8 m/s^2). Now, you can calculate the work done by multiplying the force by the distance of 100 m: work = (25 kg × 9.8 m/s^2) × 100 m = 24,500 J. Therefore, the correct answer is 24,500 J, not 2,500 J.

4. In this question, it states that your friend pushes the lawnmower four times as far as you do while exerting only half the force. Work is defined as force multiplied by distance. Since your friend is pushing with less force but a longer distance, you need to determine which value is greater: the decrease in force or the increase in distance. Comparing half the force to four times the distance, we find that the increase in distance is greater. Therefore, your friend does more work because they cover a larger distance.

7. When you push against a stationary wall, no work is done on the wall because there is no displacement (i.e., distance moved) of the wall. However, you do feel tired because your muscles are still exerting force against the wall. Your muscles are working isometrically, meaning they are contracting without experiencing any movement. This sustained contraction can lead to muscle fatigue and the feeling of tiredness.

9. The amount of work required to stretch a spring depends on its spring constant (stiffness) and the distance it is stretched. If you stretch a strong spring and a weak spring the same distance, the strong spring will require more work to stretch. This is because the spring constant of a strong spring is higher, meaning it requires more force to stretch it the same distance compared to a weaker spring with a lower spring constant. Work is directly proportional to the force applied, so a stronger spring will demand more work to stretch it the same distance.

I hope this helps! Let me know if you have any further questions.