Question 1

A projectile is shot from ground level at an angle $$	heta$$ above the horizontal. Assuming the ground is flat, which value of $$	heta$$ maximizes the distance traveled by the projectile before it hits the ground (ignore air resistance)?

Accepted Answer

$$45^\circ$$

Question 2

Anna drives around a curve in the road and slides off the side of the road. Maria drives around the same curve but does not slide. Based on the model of friction that was studied in class, which of the following could explain their different outcomes?

Accepted Answer

Anna's car has a lower coefficient of friction between the tires and the road than Maria's.

Question 3

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

Accepted Answer

$$4:1$$

Question 4

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

Accepted Answer

$$100\ \mathrm{N}$$

Question 5

Suppose a hawk and a swallow are in a mid-air collision. Which of the following is true?

Accepted Answer

The force exerted by the hawk on the bird is equal to the force exerted by the bird on the hawk.

Question 6

Suppose your mass is $$80\ \mathrm{kg}. $$You are standing on a scale in an elevator that is accelerating upward at a rate of $$2\ \mathrm{m/s^2$}. $$What does the scale read?

Accepted Answer

$$960\ \mathrm{N}$$

Question 7

Suppose an object is sliding down a frictionless ramp. The acceleration of the object is measured to be $$4.9\ \mathrm{m/s^2$}. $$What is the angle of the ramp?

Accepted Answer

$$30^\circ$$

Question 8

Suppose a driver at constant speed around a circular track with radius $$100\ \mathrm{m}. $$The coefficient of friction between tires and ground is $$1.1. $$How fast can the driver take the turn before sliding off the track?

Accepted Answer

$$32.8\ \mathrm{m/s}$$

Question 9

Anna and Bob are standing still on ice skates. Anna pushes Bob as hard as she can, and as a result both skaters move in opposite directions. If Anna has twice the mass of Bob, and Anna moves at $$1\ \mathrm{m/s}$$ after pushing, what is Bob's speed?

Accepted Answer

$$2\ \mathrm{m/s}$$

Question 10

Suppose a massless thread holds a mass connected by piece of string, hanging from the ceiling of an elevator. The elevator accelerates upward at $$2\ \mathrm{m/s^2$}. $$The mass is $$2\ \mathrm{kg}$$ and the thread can withstand a maximum tension of $$30\ \mathrm{N}$$ before it breaks. What is the maximum (upward) acceleration of the elevator before the thread breaks?

Accepted Answer

$$10.3\ \mathrm{m/s^2$}$$

Question 11

A child slides 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

$$230\ \mathrm{N}$$

Question 12

On the surface of the moon, the acceleration due to gravity is about $$1/6 of $$what it is on earth. Ignoring air resistance, if I throw one ball straight up on earth, and another one straight up on the moon, how much higher would the one on the moon go? Assume they are both released from ground level at the same velocity.

Accepted Answer

$$6$$ times higher

Question 13

Suppose instead of throwing the balls vertically, I throw them horizontally, releasing them at a height $$h$$ above the ground at the same speed. How much further would the one on the moon go before hitting the ground?

Accepted Answer

$$2.4$$ times farther

Question 14

Which of the following is true of acceleration and velocity vectors of an object undergoing uniform circular motion?

Accepted Answer

They are perpendicular

Question 15

Suppose I drop a rock off a $$15\ \mathrm{m}$$ bridge. Ignoring air resistance, how long does it take to hit the ground?

Accepted Answer

$$1.75\ \mathrm{s}$$

Question 16

Given the model for friction discussed in class, the force of kinetic friction is

Accepted Answer

Proportional to the normal force and independent of the velocity

Question 17

Suppose I apply a net force of $$15\ \mathrm{N} to an $$object with a mass of $$5\ \mathrm{kg}. $$What is its acceleration?

Accepted Answer

$$3\ \mathrm{m/s^2$}$$

Question 18

Suppose three blocks are stacked as shown: $$7\ \mathrm{kg} on $$top, $$3\ \mathrm{kg} in $$the middle, $$5\ \mathrm{kg} on $$the bottom. If you imagine the table is on earth and at rest, what is the magnitude of the force of the bottom block on the middle one?

Accepted Answer

$$100\ \mathrm{N}$$

Question 19

Suppose two vectors $$\vec{A}$$ and $$\vec{B}. $$Let $$2\vec{A} be $$the vector sum of $$\vec{A}$$ and $$\vec{B}. $$Letting $$A = 1$$ and $$B = 1$$, which of the following is true about the magnitude of $$\vec{A} + \vec{B}$$ and the magnitude of $$2\vec{A}$$?

Accepted Answer

$$|\vec{A} + \vec{B}| = \sqrt{2}$$

Physics 1401: Practice Midterm Exam Study Guide

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드