Physics Work Energy Power

A 10-kg wagon moves horizontally at an initial speed of 5 m/s. A 30-N force is applied to the wagon by pulling the rigid handle, which is angled 60° above the horizontal. The wagon continues to move horizontally for another 20 m. A negligible amount of work is converted into thermal energy. By how much has the wagon’s kinetic energy increased over the 20 m?

• 300 J

• 600 J

• 125 J

• 63 J

Tags

NGSS.HS-PS2-1

A system consists of two objects having masses m_l and m₂ (m_l < m₂). The objects are connected by a massless string, hung over a pulley as shown, and then released. When the object of mass m₂ has descended a distance h, the potential energy of the system has decreased by...

• (m₂ - m_l)gh

• m₂gh

• (m₁ + m₂)gh

• none of these

Tags

NGSS.HS-PS2-1

NGSS.HS-PS3-1

The following graphs, all drawn to the same scale, represent the net force F as a function of displacement x for an object that moves along a straight line. Which graph represents the force that will cause the greatest change in the kinetic energy of the object from x = 0 to x = x₁?

• 
• 
• 
• 

Tags

NGSS.HS-PS2-1

NGSS.HS-PS3-1

A block on a horizontal frictionless plane is attached to a spring, as shown. The block oscillates along the x-axis with amplitude A. Which of the following statements about energy is correct?

• The kinetic energy of the block is at a minimum at x =0.

• The potential energy of the spring is at a minimum at x = A.

• The potential energy of the spring is at a minimum at x = 0.

• The kinetic energy of the block is at a maximum at x = A.

Tags

NGSS.HS-PS3-2

In which of the following situations do your arms do work on books?

• holding a heavy stack of books while standing

• pushing down on a heavy stack of books lying on a table

• dropping a stack of books onto a table

• picking up a pile of books from the floor

Which are correct units for work?

• N x s

• N x m

• J/s

• W

Which are correct equivalent units for power?

• N x s

• N x m

• J

• J/s

Which principle states that whenever work is done, energy changes form?

• Law of Conservation of Energy

• Work-Energy Theorem

• Newton's Fourth Law

• Efficiency

If you pull the trolley along a flat floor horizontally. Which force do you use to calculate the work done.

• Weight

• Pulling force

• Normal forrce

• Friction

Tags

NGSS.HS-PS2-1

Winnie and Eeyore have the same mass and have just finished climbing the same tree, but Eeyore was 4 seconds faster then Winnie. Who used the most power?

• Winnie as he took the longer time and did the same amount of work as Eeyore

• Winnie as he is shorter and could grip more as so did more work overall

• Eeyore as he did the same amount of work as Winnie but in a shorter time.

• Eeyore as he did more work than Winnie but in a shorter time