Assignment:
Section: Show all the work.
1. An object of mass 3.0kg moves around a circular track at the constant speed of 20m/s. The radius of the track is 50m.
(a) Calculate the centripetal acceleration of the object.
(b) Calculate the centripetal force necessary to provide the centripetal acceleration.
2. An object with a kinetic energy of 50 J is stopped in a distance of 0.01 m. Calculate the average force necessary to stop the object.
3. A box is moved 10 m across a floor by a force of 20 N along the direction of motion. Calculate the work done by the force.
4. A pendulum swings through 10 cycles in 5 seconds.
(a) Calculate the period of the pendulum.
(b) Calculate the frequency.
5. Joe has a weight of 500 N when he is standing on the surface of the earth. What would be his weight (the gravitational force due to the earth) be if he doubles his distance from the center of the earth by flying in a spacecraft ?
6. Two 175 kg masses are separated by a distance of 3 m. Using Newton's law of gravitation, calculate the magnitude of the gravitational force exerted by one mass on the other.
7. The acceleration due to gravity on the surface of the moon is approximately 1/6 that at the surface of the earth. Calculate:
(a) The weight of an astronaut whose weight on the surface of the earth is 600 N.
(b) The mass of the astronaut.
8. A box of mass 6 kg is lifted (without acceleration) through a height of 5.0 m in order to place it upon a shelf of a closet.
(a) What is the increase in gravitational potential energy of the box ?
(b) How much work was required to lift the box in this position ?
9. At the low point in its swing, a pendulum bob with a mass of 0.4 kg has a speed of 11 m/s.
(a) Calculate its kinetic energy at the low point.
(b) Ignoring air resistance, how high will the bob swing above the low point before reversing direction?
10. A spring is stretched by a distance of 0.20 m from its original unstretched position by a force of 8.0N.
(a) Calculate the spring constant.
(b) Calculate the increase in elastic potential energy of the spring.
11. A box is moved across a floor by 10 m along a straight line by applying a horizontal force of 20 N. The force of friction acting on the box in the opposite direction is 5 N.
(a) Calculate the work done by F.
(b) Calculate the work done by f.
(c) Calculate the work done by N.
(d) Calculate the work done by the gravitational force.
(e) Calculate the total work done on the object.
(f) What is the change in kinetic energy of the object.
(g) If the object starts from rest, calculate its speed at the end of 10 m displacement.