A block of mass m = 2.50 kg is pushed d = 2.60 m along a...

A block of mass $m = 2.50$ kg is pushed $d = 2.60$ m along a frictionless horizontal table by a constant applied force of magnitude $F = 11.0$ N directed at an angle \theta$= 25.0^\circ$ below the horizontal as shown in the figure below. (a).Determine the work done by the applied force. is within 10% of the correct value. This may be due to roundoff error, or you could have a mistake in your calculation. Carry out all intermediate results to at least four-digit accuracy to minimize roundoff error. J (b) Determine the work done by the normal force exerted by the table. J (c) Determine the work done by the force of gravity. J (d) Determine the work done by the net force on the block. J

Transcript

00:01 As shown in the diagram, shown with the blue color, it is a block of mass 2 .5 kg held on it, means frictionless surface.

00:20 The surface is shown with the red color.

00:23 So here, coefficient of friction is zero.

00:27 On this block, a force of 25 newton is acting on the, line shown here it is acting on the top left corner and the force is acting at an angle of 25 degree with the horizontal force is inclined at an angle of 25 degree and the means blocks moves with a distance of two meter in this direction right so final position of the block is shown by the dotted color so here the first point is they are asking the work done by the applied force.

01:17 Now we know that the work done is equal to component of force in the direction of the motion.

01:25 Now this is the force f, right? and its component in the direction of b will be in this direction, its component will be here f cost theta, f cost 25 is the component of f in the direction of the displacement.

01:46 So work done will be f cos 25 multiplied by the news distance and this is distance.

02:00 Now we put the values f is 20 newton f is yeah f is 20 20 newton f is f is 20 f is 20 f is 20 newton f is 20 newton, so this will be 20 into cost 25 multiplied by the distance is 2 meters.

02:25 So it comes out to be 36 .25 jules.

02:32 Right.

02:33 Now second case, they asked the work done by the normal force.

02:38 Now, what is a normal force? normal force is indicated by n.

02:43 This is the force.

02:46 A force, a perpendicular to the surface where the block is resting and this is the force exerted by this surface on the block.

02:58 So from the standard definition of the work, work equal to force, force is normal force right into the distance 2 meter multiplied by cause of angle between normal force and displacement.

03:15 Now normal force is vertically up while displacement is means along the axis.

03:23 So angle between them is this which is 90 degree.

03:27 So it means this will be cost 90, cost 90, say zero.

03:32 So work done by the normal force will be zero, work done by the applied force.

03:37 We have already calculated.

03:40 Now in the third case, they are asking about work done by the force of gravity...

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