Question

In which of the following cases is work being done on an object? Question 2 options: Pushing against a locked door Carrying a box down a corridor Pulling a trailer up a hill Suspending a heavy weight with a strong chain

Answer 1

Question 1  

In order to do work, the force vector must be

in the same direction as the displacement vector and the motion.

Question 2  

In which of the following cases is work being done on an object?

Pulling a trailer up a hill

Question 3  

Which situation is an example of NOT doing work?

carrying a box

Question 4  

Work is measured in

Joules

Question 5  

To find the work done, the force exerted and distance moved are multiplied. A couch is moved twice before you are happy with its placement. The same force was used to move the couch both times. If more work is done the first time it is moved, what do you know about the distance it was moved?

When more work was done, the couch was moved further.

Question 6  

A weight lifter raises a 1600 N barbell to a height of 2.0 meters. How much work was done? W = Fd

3200 Joules

Question 7  

You and a friend (Alex) are at a a tree-top adventure park .. . . part of the course requires you to climb up a rope. You both climb the same rope in the same amount of time. However, the tension in the rope is greater

when Alex climbs. Who did the most work?

Alex did - more tension means more force - more force means more work was done  

Question 8  

Doing work at a faster rate creates power.

more

Question 9  

In one challenge on the Titan Games, competitors have to lift 200 pounds up a long ramp. Angel is able to move the weight in 42 seconds. Anthony gets it done in only 38 seconds. Which statement is true?

Anthony has more power than Angel.  

Question 10  

A mountain climber exerts 41,000 J of work to climb a cliff. How much power does the climber need if she wants to finish in only 500 seconds? Power = Work / time

82 Watts

Question 11  

Your family is moving to a new apartment. While lifting a box 83 Joules of work is done to put the box on a truck, you exert an upward force of 75 N for 3 s. How much power is required to do this? (Hint: You only need two of the 3 numbers given!) Power = Work / time

27.7 Watts

*100% CORRECT ANSWERS

Answer 2

As we know that work done is defined as product of force and displacement in the direction of applied force

so we can say it is

$W = F.d$

or we can say

$W = Fdcos\theta$

so we will have following options

A)Pushing against a locked door

There is no work done in above case as there will be no displacement in that case so work done is ZERO

B) Carrying a box down a corridor

While we move done and carrying a box then work done by gravity on the box while our work done is negative work.

C) Pulling a trailer up a hill

In above case our work done to pull a box up a hill is positive work as we need to work against gravity

D)  Suspending a heavy weight with a strong chain

During suspension there is no displacement so there will be no work done in above case

so correct answer will be

Pulling a trailer up a hill