I need help understanding these, please. Thanks!
1. A 2 kg body moves with constant velocity when a force of 10 N is applied. What is the coefficient of kinetic friction between the table and the body? (Would I use F=m*g for this??)
2. Which of the following statements is correct for the law of conservation of energy?
a. Initial potential energy always equals to final potential energy.
b. Initial kinetic energy always equals to final kinetic energy.
c. Initial mechanical energy always equals to final mechanical energy.
d. Initial mechanical energy always equals to final mechanical energy in the absence of friction.
3. A car takes a sharp turn on a road. Which of the following provides the centripetal force on the car?
a.weight of the car
b.frictional force
c.tangential acceleration
d.gravitational force
Thanks again so much!!
Oh my, one by one:
1. A 2 kg body moves with constant velocity when a force of 10 N is applied. What is the coefficient of kinetic friction between the table and the body? (Would I use F=m*g for this??)
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F = m a
but a = 0
so there is no net force
10 N + Friction force = 0
so friction force = -10 N
so
10 = mu m g
mu = 10/(2*9.81)
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2. Which of the following statements is correct for the law of conservation of energy?
d. Initial mechanical energy always equals to final mechanical energy in the absence of friction.
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3. A car takes a sharp turn on a road. Which of the following provides the centripetal force on the car?
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What happens if the road is icy and the tires are bald?
b.frictional force
Thank you so much Damon!
1. To find the coefficient of kinetic friction, we need to use the formula:
Friction force = coefficient of kinetic friction * normal force
The normal force is the force exerted by the table on the body and is equal to the force of gravity (weight) when the object is on a flat surface. The weight can be calculated using the formula:
Weight = mass * acceleration due to gravity
In this case, the body's mass is given as 2 kg. The acceleration due to gravity is approximately 9.8 m/s^2. Therefore, the weight can be calculated as:
Weight = 2 kg * 9.8 m/s^2 = 19.6 N
The force applied is given as 10 N. Since the body is moving with constant velocity, the applied force must be equal and opposite to the friction force:
Friction force = 10 N
Now we can substitute the values into the formula to find the coefficient of kinetic friction:
10 N = coefficient of kinetic friction * 19.6 N
Solving for the coefficient of kinetic friction:
coefficient of kinetic friction = 10 N / 19.6 N ≈ 0.51
So, the coefficient of kinetic friction between the table and the body is approximately 0.51.
2. The correct statement for the law of conservation of energy is: (c) Initial mechanical energy always equals to final mechanical energy.
According to the law of conservation of energy, total mechanical energy remains constant in a system where only conservative forces are present. Mechanical energy is the sum of potential energy and kinetic energy. So, if there is no non-conservative force like friction acting on the system, the initial mechanical energy should be equal to the final mechanical energy.
Therefore, the correct option is (c) Initial mechanical energy always equals to final mechanical energy.
3. The centripetal force on the car is provided by:
Option (b) Frictional force
When a car takes a sharp turn, it experiences a centripetal force that keeps it moving in a circular path. This force is provided by the friction between the car's tires and the road. Friction acts as a centripetal force, pulling the car inward towards the center of the turn.
Therefore, the correct option is (b) Frictional force.