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3 years ago

7

Paul’s 10 kg baby sister Susan sits on a mat. Paul pulls the mat across the floor using a rope that is angled 30° above the floo

r. The tension is a constant 30 N and the coefficient of kinetic friction is 0.20. Use work and energy to find Susan’s speed after being pulled 3.0 m.

2 answers:

kifflom [539]3 years ago

5 0

Answer: speed= 1.95866m/s ~= 2.0 m/s

Explanation: check attachment for explanation

kiruha [24]3 years ago

4 0

Answer:

The speed of Susan is 2.37 m/s

Explanation:

To visualize better this problem, we need to draw a free body diagram.

the work is defined as:

$W=F*d*cos(\theta)$

here we have the work done by Paul and the friction force, so:

$W_p=F_p*d*cos(0)\\F_p=30N*cos(30^o)=26N\\W_p=26*3*(1)=78J$

$W_f=F_f*d*cos(180)\\F_f=\µ*(10*9.8-30N*sin(30^o))=16.6N\\W_p=16.6*3*(-1)=50J$

Now the change of energy is:

$W_p-W_f=\frac{1}{2}m*v^2\\v=\sqrt{\frac{2(78J-50J)}{10kg}}\\v=2.37m/s$

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3 years ago

A piano tuner sounds two strings simultaneously. One has been previously tuned to vibrate at 293.0 Hz. The tuner hears 3.0 beats

ololo11 [35]

Answer:

Part a)

$f_B = 290 Hz$

Part B)

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Explanation:

Part a)

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Part B)

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now we have

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3 years ago

A combination lock has a 1.3-cm-diameter knob that is part of the dial you turn to unlock the lock. To turn that knob, you twist

galina1969 [7]

Answer:

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r = Radius of knob = $\frac{d}{2}=\frac{1.3}{2}=0.65\ cm$

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$F=N\mu\\\Rightarrow F=5\times 0.65\\\Rightarrow F=3.25\ N$

When we multiply force and radius we get torque

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$\tau_t=F\times r\\\Rightarrow \tau_t=3.25\times 0.0065\\\Rightarrow \tau_t=0.021125\ Nm$

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$\tau_f=F\times r\\\Rightarrow \tau_f=3.25\times 0.0065\\\Rightarrow \tau_f=0.021125\ Nm$

The total torque is given by

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The most torque that exerted on the knob is 0.04225 Nm

4 0

2 years ago

A boat has a mass of 4040 kg. Its engines generate a drive force of 4660 N due west, while the wind exerts a force of 880 N due

maxonik [38]

Answer:

Explanation:

Given:

Mass of the boat, m = 4040 kg

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The force of water, Fwa = 1400 N in east = -1400N

Total three forces are acting on the boat

Fnet= Fb+fwi+Fwa

Fnet= 4660 - 880 - 1400

Fnet= +2380N

Acceleration (a) = Force/mass

= 2380/4040

= 0.59m/s2

6 0

3 years ago

Read 2 more answers