Answer:
- 1100 J heat flows out
Explanation:
dW = - 1600 J (as work is done on the gas)
dU = 500 J
dQ = ?
According to the first law of thermodynamics
dQ = dU + dW
dQ = 500 - 1600
dQ = - 1100 J
As heat is negative so it flows out.
If the coefficient of static friction is 0.3, then the minimum force required to get it moving is equal in magnitude to the maximum static friction that can hold the body in place.
By Newton's second law,
• the net vertical force is 0, since the body doesn't move up or down, and in particular
∑ <em>F</em> = <em>n</em> - <em>mg</em> = <em>n</em> - 50 N = 0 ==> <em>n</em> = 50 N
where <em>n</em> is the magnitude of the normal force; and
• the net horizontal force is also 0, since static friction keeps the body from moving, with
∑ <em>F</em> = <em>F'</em> - <em>f</em> = <em>F'</em> - <em>µn</em> = <em>F'</em> - 0.3 (50 N) = 0 ==> <em>F'</em> = 15 N
where <em>F'</em> is the magnitude of the applied force, <em>f</em> is the magnitude of static friction, and <em>µ</em> is the friction coefficient.
Answer:
the the right because opposites attract to each other
Refer to the diagram shown below.
At A, the boy begins walking up the stairs.
At B, the boy is at the top of the slide. He has acquired PE (potential energy).
The value of the PE is
(50 kg)*(9.8 m/s²)*(11.5 m) = 5635 J
At C, the boy has KE (kinetic energy).
The value of the KE is
(1/2)*(50 kg)*(12 m/s)² = 3600 J
Energy is lost between B and C due to friction.
The lost energy is
5635 - 3600 = 2035 J
The distance traveled along the slide is 108 m.
If F = the average frictional force, then
(F N)*(108 m) = 2035 J
F = 18.84 N
Answers:
(a) The mechanical energy lost by sliding is 2035 J.
(b) The average frictional force is 18.84 N