Uncover valuable information and solutions with IDNLearn.com's extensive Q&A platform. Our platform provides detailed and accurate responses from experts, helping you navigate any topic with confidence.

19. A pile driver with a weight of 8,000 Newtons moves up and down at a velocity of 6 m/s. What is the kinetic energy?

20. A man is pulling a sled 20 feet with a force of 200 pounds at an angle of 40°. How much work is he doing?


Sagot :

### Question 19: Kinetic Energy

To determine the kinetic energy of the pile driver, follow these steps:

1. Determine the weight of the pile driver:
- The weight [tex]\( W \)[/tex] is given as 8,000 Newtons.

2. Identify the velocity of the pile driver:
- The velocity [tex]\( v \)[/tex] is given as 6 m/s.

3. Understand the relationship between weight, mass, and gravity:
- The weight [tex]\( W \)[/tex] is related to the mass [tex]\( m \)[/tex] via the equation [tex]\( W = m \cdot g \)[/tex], where [tex]\( g \)[/tex] represents the acceleration due to gravity (9.8 m/s^2).

4. Calculate the mass:
[tex]\[ m = \frac{W}{g} = \frac{8000 \text{ N}}{9.8 \text{ m/s}^2} = 816.3265306122448 \text{ kg} \][/tex]

5. Use the kinetic energy formula:
- Kinetic energy [tex]\( KE \)[/tex] is given by [tex]\( KE = 0.5 \cdot m \cdot v^2 \)[/tex].

6. Substitute the values:
[tex]\[ KE = 0.5 \cdot 816.3265306122448 \text{ kg} \cdot (6 \text{ m/s})^2 = 14693.877551020407 \text{ Joules} \][/tex]

Thus, the kinetic energy of the pile driver is approximately 14,693.88 Joules.

### Question 20: Work Done

To determine the work done by the man pulling the sled, follow these steps:

1. Convert the distance from feet to meters:
- The distance [tex]\( d \)[/tex] is given as 20 feet.
- Use the conversion [tex]\( 1 \text{ foot} = 0.3048 \text{ meters} \)[/tex].
[tex]\[ d = 20 \text{ feet} \times 0.3048 \text{ m/foot} = 6.096 \text{ meters} \][/tex]

2. Convert the force from pounds to Newtons:
- The force [tex]\( F \)[/tex] is given as 200 pounds.
- Use the conversion [tex]\( 1 \text{ pound} = 4.44822 \text{ Newtons} \)[/tex].
[tex]\[ F = 200 \text{ pounds} \times 4.44822 \text{ N/pound} = 889.644 \text{ Newtons} \][/tex]

3. Convert the angle from degrees to radians:
- The angle [tex]\( \theta \)[/tex] is given as 40°.
- Use the conversion [tex]\( 1° = \frac{\pi}{180} \text{ radians} \)[/tex].
[tex]\[ \theta = 40° \times \frac{\pi}{180} = 0.6981317007977318 \text{ radians} \][/tex]

4. Use the work done formula:
- Work [tex]\( W \)[/tex] is given by [tex]\( W = F \cdot d \cdot \cos(\theta) \)[/tex].

5. Substitute the values:
[tex]\[ W = 889.644 \text{ N} \cdot 6.096 \text{ meters} \cdot \cos(0.6981317007977318) = 4154.465712210038 \text{ Joules} \][/tex]

Thus, the work done by the man pulling the sled is approximately 4,154.47 Joules.
We appreciate your participation in this forum. Keep exploring, asking questions, and sharing your insights with the community. Together, we can find the best solutions. IDNLearn.com is your go-to source for dependable answers. Thank you for visiting, and we hope to assist you again.