Consider two slides, both of the same height. One is long and the other is short. From which slide will a child have a greater final speed when sliding off? Assume that there is no friction acting.
1.The child on the longer slide will have a greater final speed.
2.The child on the shorter slide will have a greater final speed.
3.The final speed will be the same for the child on the longer slide as it is for the children on the shorter slide.
4.We cannot tell from the information given.
[Ques. 2] A block of mass m is projected across a horizontal surface with an initial speed v. It slides until it stops due to the friction force between the block and the surface. The surface is now tilted at 20 and the block is projected up the surface with the same initial speed, v. Assume that the friction force remains the same as when the block was sliding on the horizontal surface. When the block comes to rest momentarily, how does its total mechanical energy compare to the case where the block slid horizontally comes to rest?
1.It is the same.
2.It is less in the case where the block went up the slope.
3.It is more in the case where the block went up the slope.
4.We cannot tell from the information given.
[Ques. 3] A block of mass m is projected across a horizontal surface with an initial speed v. It slides until it stops due to the friction force between the block and the surface. The same block is now projected across the horizontal surface with an initial speed v/2. When the block has come to rest, how does the distance from the projection point compare to that in the first case?
1.It is the same.
2.It is half as large.
3.It is one fourth as large.
4.It is none of these.
[Ques. 4] A rock of mass m is dropped to the ground from a height h. A second rock, with mass 3m, is dropped from the same height. When the second rock strikes the ground, its kinetic energy is
1.the same as that of the first rock.
2.three times that of the first rock.
3.six times that of the first rock.
4.nine times that of the first rock.
[Ques. 5] Which of the following is (are) conserved in an isolated system?
1.the kinetic energy alone
2.the potential energy alone
3.both the potential energy and the kinetic energy
4.the sum of the kinetic energy and the potential energy
[Ques. 6] When we analyze situations that involve the kinetic and potential energies of falling objects, we identify the system as<--EndFragment--> e?
1.only the Earth.
2.only the falling object.
3.both the earth and the falling object.
4.none of these.
[Ques. 7] The gravitational potential energy of a system
1.depends on the reference configuration for zero potential energy.
2.is always positive.
3.is always negative.
4.is none of these.
[Ques. 8] A certain uniform spring has a constant k. Now the spring is cut in half. What is the relationship between k and the spring constant k of each resulting smaller spring?
1. Each k = k/2
2. Each k = 2k
3. Each k = k/4
4. Each k = 4k
[Ques. 9] Discuss whether any work is being done by each of the following agents and, if so, whether the work is positive or negative.
(i) a chicken scratching on the ground
(ii) a person studying physics
(iii) a crane lifting a bucket of concrete
(iv) the gravitational force on the bucket in (iii)
(v) the leg muscles of a person in the act of sitting down
1.All of them do work. Positive work is done in cases (i), (ii), and (iii) and negative work is done in cases (iv) and (v).
2.No work is done in case (ii). Positive work is done in cases (i) and (iii) and negative work is done in cases (iv) and (v).
3.No work is done in cases (i) and (ii). Positive work is done in case (iii) and negative work is done in cases (iv) and (v).
4.No work is done in cases (i) and (ii). Positive work is done in cases (iii) and (v) and negative work is done in case (iv).
[Ques. 10] You go out for a burger with some friends. At the restaurant the waiter serves you your burger on a plate. You pick up the burger with your hand and lift it to your mouth. About how much power did you expend when you lifted the burger to your mouth from the plate?
1.0.1 watts
2.1 watt
3.10 watts
4.100 watts
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