Physics 100 Extra Practice Problems
(15 questions)

The grading button and a description of the scoring criteria are at the bottom of this page. The following problems are all PHYS 100 exam-like problems, but they have not been used in an actual exam. Click here to see the formula sheet that came with the exam.

Unless otherwise stated, ignore air resistance and assume the acceleration of gravity is g = 9.81 m/s2 vertically downward.

QUESTION 1*

Two students, S1 and S2, are rushing to class. They are waiting for green light at the same intersection. As soon as the light turns green, both students start walking with constant acceleration. The acceleration of student S1 is a1, and the acceleration of student S2 is a2, When student S1 has reached a velocity v1, she has walked a distance D1, while student S2 has walked a distance D2 = 1/3D1.

In terms of v1 and D1, what is the correct expression for a2, the acceleration of student S2?

(a)   a2 = 1/2*(v1)2/D1
(b)   a2 = g
(c)   a2 = 1/6*(v1)2/D1
(d)   a2 = 1/12*(v1)2/D1
(e)   a2 = 2/3*(v1)2/D1

QUESTION 2*

This question and the next two are about flights between Paris and Copenhagen, see figure. Copenhagen is located 780 km North and 810 km East of Paris. A flight from Paris to Copenhagen takes two hours. Typically the wind blows from East to West over Europe, but the speed varies. For one particular flight, the wind speed was 165 km/h.

What is the magnitude of vpa, the plane's velocity with respect to the air?

(a)   vpa = 800 km/h
(b)   vpa = 691 km/h
(c)   vpa = 458 km/h
(d)   vpa = 630 km/h
(e)   vpa = 960 km/h

QUESTION 3*

What is θ1, the direction of vpa with respect to East?

(a)   θ1 = 43.9°
(b)   θ1 = 46.8°
(c)   θ1 = 74.4°
(d)   θ1 = 15.6 °
(e)   θ1 = 34.4 °

QUESTION 4*

Another day, the speed of the wind has changed to 182 km/h, still the Paris to Copenhagen flight time is two hours. How does θ2, the direction of vpa on this day, compare to θ1?

(a)   θ2 < θ1
(b)   θ2 = θ1
(c)   θ2 > θ1

QUESTION 5*

The following two questions pertain to the situation described below, see also figure. A red ball and green ball are both thrown from the ground. The red ball is thrown with an initial speed of 20 m/s at an angle θ = 20° with respect to horizontal. The green ball is thrown at an angle θ = 40 m/s with respect to horizontal with the speed vg. The two balls have the same mass and are observed to hit the ground at the same time. What is vg, the initial speed of the green ball?

(a)   10.0 m/s
(b)   10.6 m/s
(c)   16.3 m/s
(d)   24.5 m/s
(e)   37.6 m/s

QUESTION 6*

If the red ball travels a distance dr before it hits the ground, and the green ball travels a distance dg before it hits the ground, how does dr compare to dg?

(a)   dr < dg
(b)   dr = dg
(c)   dr > dg

QUESTION 7*

The following two questions pertain to the situation described below, see also figure. Three blocks, A, B, and C with masses mA = 4 kg, mB = 3 kg, and mC = 2 kg, respectively are stacked on top of each other in an elevator as shown in the figure. In case I, the elevator is accelerating upward with acceleration a, while in case II the elevator is accelerating downward with acceleration a. How does FAonB(II), the magnitude of the force that block A exerts on block B in case II, compare to FAonB(I), the magnitude of the force that block A exerts on block B in case I?

(a)   FAonB(II) < FAonB(I)
(b)   FAonB(II) = FAonB(I)
(c)   FAonB(II) > FAonB(I)

QUESTION 8*

We are now changing case I in two ways: firstly, we interchange bloks B and C; and, secondly, the elevator is now accelerating downward with acceleration a (see figure). Case II is the same as in the previous question. How does FBonC(II), the magnitude of the force that block B exerts on block C in case II, compare to FConB(I), the magnitude of the force that block C exerts on block B in case I?

(a)   FBonC(II) < FConB(I)
(b)   FBonC(II) = FConB(I)
(c)   FBonC(II) > FConB(I)

QUESTION 9*

The following two questions pertain to the following situation.

Planet X has two mooons, Alpha and Beta, both orbiting the X in uniform circular motion. The mass and the radius of Planet X are respevtively MX = 3.2·1025 kg and RX = 5200 km.

If the mass of moon Alpha is mα = 4.1·1021 kg and its period is Pα = 2 days, what is the d, the distance from the center of Alpha to the surface of planet X?

(a)   d = 167000 km
(b)   d = 54815 km
(c)   d = 5200 km
(d)   d= 117000 km
(e)   d= 112000

QUESTION 10*

Moon Beta is orbiting planet X with speed vβ at a distance rβ.

If vβ = 2vα, where vα is the speed of moon Alpha, how does rα, the orbital radius of Alpha, compare to rβ?

(a)   rα > 2rβ
(b)   rα = 2rβ
(c)   rα < 2rβ

QUESTION 11*

The following three questions pertain to the following situation:

A block of mass m = 1.5 kg is sliding down a rough ramp that makes an angle θ = 35° wrt. to horizontal, as shown. Starting from rest, the block is observed to cover a distance d = 50 cm in the time t = 1.7 s.

What is the value of μk, the coefficient of kinetic friction between the block and the ramp?

(a)   μk = 0.627
(b)   μk = 0.743
(c)   μk = 1.37
(d)   μk = 0.657
(e)   μk = 0.538

QUESTION 12

Keeping θ, d, and t constant, how would μk change if the mass of the block were dobbled?

(a)   μk would decrease
(b)   μk stay the same
(c)   μk increase

QUESTION 13

Keeping m, θ, and d constant, how would μk change if t, the time it takes the block to slide the distance d, were increased?

(a)   μk would decrease
(b)   μk stay the same
(c)   μk increase

QUESTION 14*

The next two questions pertain to the following situation:

A block of mass m = 1.5 kg is kept in place on a rough ramp by a spring, as shown. The ramp makes an angle θ = 50° wrt. to horizontal, and the coefficients of static and kinetic frictions are μs = 0.65 and μk = 0.3, respectively. The spring constant is k = 40N/m.

What is Δxmin, the minimum amount the spring must be stretched in order for the block to be at rest?

(a)   Δxmin = 0.043 m
(b)   Δxmin = 0.053 m
(c)   Δxmin = 0.13 m
(d)   Δxmin = 0.17 m
(e)   Δxmin = 0.21 m

QUESTION 15*

Keeping everything else the same, how would Δxmin change if μs, the coefficient of static friction, decreased?

(a)   Δxmin would decrease
(b)   Δxmin would stay the same
(c)   Δxmin would increase