1) While a boat is being towed at a speed of 10 m/s, the tension in the towline

Question

1) While a boat is being towed at a speed of 10 m/s, the tension in the towline is 6.2 kN. What is the power supplied to the boat through the towline?

2) A horse draws a sled horizontally across a snow-covered field. The coefficient of friction between the sled and the snow is 0.195, and the mass of the sled, including the load, is 185.5kg. If the horse moves the sled at a constant speed of 1.666 m/s, what is the power needed to accomplish this?

3)A spring with a spring constant of 233.9 N/m is compressed by 0.208 m. Then a steel ball bearing of mass 0.0381 kg is put against the end of the spring, and the spring is released. What is the speed of the ball bearing right after it loses contact with the spring? (The ball bearing will come off the spring exactly as the spring returns to its equilibrium position. Assume that the mass of the spring can be neglected.)

4)An ideal spring has the spring constant k = 304 N/m. Calculate the distance this spring must be stretched from its equilibrium position for 24 J of work to be done.

(a) How much work is done by the force?

(b) If the mass has a speed of 9 m/s at x = 4 m, what is its speed at x = 8 m?

6)A constant force,

7)A 63-kg refrigerator rests on the floor. How much work is required to move it at constant speed for 4.5 m along the floor against a friction force of 170 N?

Explanation / Answer

1) Power=F*v=6200*10=62000 W

2) F=185.5*9.8*0.195=354.49 N

==> power=354.49*1.666=590.58 W

3) 0.5 kx^2=0.5 mv^2

==> v=16.297 m/s

4) 0.5 kx^2=24

==> x=0.397m=39.7cm

5) W=integration of F.dx from x=4 to x=8

==> W=x^4/2from x=4 to x=8

==> W=1920 J

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