Question 1

A projectile is launched from ground level at an angle $$	heta$$ above the horizontal. Neglecting air resistance, which launch angle maximizes the horizontal distance traveled by the projectile before it lands?

Accepted Answer

$$45^\circ$$

Question 2

Maria drives around a curve in the road and slides off the side of the road. If the coefficient of static friction between Maria's tires and the road was lower than Ann's, what can you conclude?

Accepted Answer

Ann's car was traveling faster than Maria's.

Question 3

Suppose you travel 1 mile north, then one mile northeast, then one mile southeast. How far are you from your starting point?

Accepted Answer

$$\sqrt{2}$$ miles

Question 4

Suppose projectile 1 is shot straight up, and projectile 2 is shot at a $$30^\circ$$ angle with respect to the horizontal at the same speed. What is the ratio of the maximum height achieved by projectile 1 to that achieved by projectile 2?

Accepted Answer

$$2:1$$

Question 5

Two people pull with a force of 100 newtons on opposite sides of a rope. What is the tension in the rope?

Accepted Answer

100 newtons

Question 6

You are standing on a scale in an elevator that is accelerating upward at $$2\,\mathrm{m/s^2$}. If $$your mass is $$60\,\mathrm{kg}$$, what does the scale read?

Accepted Answer

$$72\,\mathrm{kg}$$

Question 7

An object is sliding down a frictionless ramp. The acceleration of the object is measured to be $$4\,\mathrm{m/s^2$}. $$What is the angle of the ramp?

Accepted Answer

$$30^\circ$$

Question 8

You drive at constant speed around a circular track with radius $$100$$ meters. The coefficient of static friction between your tires and the ground is $$1.1. $$How fast can you drive before sliding off the track?

Accepted Answer

$$33\,\mathrm{m/s}$$

Question 9

Anna and Bob are standing still on ice skates. Anna pushes Bob as hard as she can, and as a result he starts moving at $$1\,\mathrm{m/s}$$ per second. Anna weighs $$60\,\mathrm{kg}$$ and Bob weighs $$80\,\mathrm{kg}. $$How fast does Anna move as a result of pushing Bob? (Assume no friction.)

Accepted Answer

$$0.75\,\mathrm{m/s}$$

Question 10

Suppose three beads are connected by pieces of string, hanging from the ceiling of an elevator as shown. Each bead has a mass of $$1\,\mathrm{kg}$$, and the string can have a maximum tension of $$40\,\mathrm{N}$$ before it breaks. What is the maximum (upward) acceleration of the elevator before the string breaks?

Accepted Answer

$$1.6\,\mathrm{m/s^2$}$$

Question 11

A child sleds down a $$20^\circ$$ snow slope. The child and sled together weigh $$25\,\mathrm{kg}. $$What is the magnitude of the normal force that the snow exerts on the bottom of the sled?

Accepted Answer

$$235\,\mathrm{N}$$

Question 12

If you fire a projectile at $$25\,\mathrm{m/s} at an $$angle of $$30^\circ$$ above the ground, how far does it go before it lands? (Neglect air resistance, assume ground is flat, and $$g = 9.8\,\mathrm{m/s^2$}.)$$

Accepted Answer

$$55.6$$ meters

Question 13

Suppose you did not take into account the initial height of the object when calculating projectile range. How would your answer to question 14 change?

Accepted Answer

It would be lower

Question 14

Suppose the coefficient of static friction between an object and the table is $$0.4. To $$what angle can I tilt the table without the object sliding?

Accepted Answer

$$	an$$^{-1}$$(0.4)$$

Question 15

Suppose you have two vectors $$\vec{A}$$ and $$\vec{B}. $$Let $$\vec{C} be $$the vector sum of $$\vec{A}$$ and $$\vec{B}. $$Letting $$A = |\vec{A}|$$, $$B = |\vec{B}|$$, and $$C = |\vec{C}|$$, which of the following is true?

Accepted Answer

$$C \leq |A| + |B|$$

Question 16

Suppose you throw a rock off a $$15$$ meter bridge. Ignoring air resistance, how long does it take to hit the ground?

Accepted Answer

$$1.24$$ seconds

Question 17

Suppose you are driving around a circular track with radius $$40$$ meters at a speed of $$15\,\mathrm{m/s}. $$What is the magnitude of your centripetal acceleration?

Accepted Answer

$$3.75\,\mathrm{m/s^2$}$$

Question 18

Suppose a bird has a mid-air collision with a bee. Which of the following is true?

Accepted Answer

The forces are equal in magnitude and opposite in direction.

Question 19

Suppose you are standing on a scale in an elevator that is accelerating downward at $$2\,\mathrm{m/s^2$}. If $$your mass is $$60\,\mathrm{kg}$$, what does the scale read?

Accepted Answer

$$48\,\mathrm{kg}$$

Fundamental Concepts in Introductory Physics: Mechanics, Forces, and Motion

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