Work and power review

Work is?

• the total energy in an object

• the change of energy in an object

• force

• energy

Tags

NGSS.HS-PS3-1

An object has a mass of 12kg. What is the minimum amount of force needed to lift the object?

• 9.8 N

• 117.6 N

• 12 N

• 118 N

Tags

NGSS.HS-PS2-1

Calculate the amount of gravitational potential energy of a 8 kg ball held 30 m in the air.

• 2352 J

• 0 J

• 9.8 J

• 78.4 J

Tags

NGSS.HS-PS2-4

You throw a ball down from the top of a building. When is negative and positive work done on the ball?

• - when you throw it down

  • + by gravity as it falls

• • - by gravity as it falls

  • + when you throw it down

• both you throwing the ball and gravity are doing + work

• both you throwing the ball and gravity are doing -work

You slide into home base. Which force does negative work?

• the normal force from the ground

• the push force from your legs as you jump

• the friction force while you slide

• no negative work is done

You slide into home base. Which force does no work on you as you slide?

• the normal force from the ground

• the friction force as you slide

• the push force from your legs

• all of the forces do work on your body

If your 1500kg car has 675000J of kinetic energy, how fast is it moving?

• 900 m/s

• 30 m/s

• 225 m/s

• do not know enough

Tags

NGSS.HS-PS3-1

You are sail boating. Your boat has 3,000 J of kinetic energy. The wind blows and does 1,500J of work on your boat. How much kinetic energy does your boat have now?

• 4,500J

• 1,500J

• 4,500,000J

• 2J

Tags

NGSS.HS-PS3-1

A 320W crane must lift a 9kg crate 10m in exactly 5 seconds. Can it do it? If not does it have too much power or too little?

• no, the crane does not have enough power

• no, the crane has too much power

• yes!

• we need more information

Tags

NGSS.HS-PS2-1

A car can gain 540,000J of kinetic energy over a distance of 20m. How much force is delivered to the wheels by the engine?

• 27,000 N

• 10,800,000 N

• 540,000 N

• 1200 N

Tags

NGSS.HS-PS2-1