Q: What is the gravitational force acting on a $$50\ \mathrm{kg}$$ person due to another $$50\ \mathrm{kg}$$ person standing $$5.0\ \mathrm{m}$$ away?

$$6.67 \times 10$$^{-8}$$\ \mathrm{N}$$

Q: A planet has an airless moon that is $$2.0 \times 10^4$\ \mathrm{m} in $$diameter. Experiments reveal that a freely falling object near the moon's surface accelerates at $$5.0\ \mathrm{m/s^2$}. $$What is the mass of the moon?

$$8.75 \times 10$$^{18}$$\ \mathrm{kg}$$

Q: The coefficient of linear expansion for lead is $$29 \times 10$$^{-6}$$\ \mathrm{K}^{-1}. $$What is its coefficient of volume expansion?

$$87 \times 10$$^{-6}$$\ \mathrm{K}^{-1}$$

Question 1

A marathon runner covers a distance of 40.0 km in 1 hour and 41 minutes. What is the runner's average speed in m/s?

Accepted Answer

$$2.96\ \mathrm{m/s}$$

Question 2

Two vectors $$\vec{A}$$ and $$\vec{B}$$ have components $$\vec{A} = 2\hat{i} + 4\hat{j}$$ and $$\vec{B} = 3\hat{i} + 8\hat{j}. $$What is $$\vec{A} - \vec{B}$$?

Accepted Answer

$$(-1\hat{i} - 4\hat{j})$$

Question 3

A 50.0 kg person stands on a scale in an elevator. The scale reads 500 N. What is the magnitude of the acceleration of the elevator?

Accepted Answer

$$0.19\ \mathrm{m/s^2$}$$

Question 4

A 1000 kg car is moving at a speed of 50.0 m/s. What is the minimum work required to stop the car?

Accepted Answer

$$125000\ \mathrm{J}$$

Question 5

Two cars, one with mass 8.0 kg moving at 2.0 m/s and another with mass 2.0 kg at rest, collide head-on and stick together. What is their final velocity after the collision?

Accepted Answer

$$2.0\ \mathrm{m/s}$$

Question 6

A wheel with a moment of inertia of $$10.0\ \mathrm{kg\cdot m^2$}$$ starts from rest and accelerates under a constant angular acceleration of $$0.6\ \mathrm{$$rad/s^2$$}$$ for 4.0 s. What is the wheel's rotational kinetic energy at the end of 4.0 s?

Accepted Answer

$$28.8\ \mathrm{J}$$

Question 7

A rotating wheel slows down with a constant angular acceleration of $$-3.0\ \mathrm{$$rad/s^2$$}$$ from an initial angular velocity of $$20\ \mathrm{rad/s} to $$rest. How many revolutions does it make before stopping?

Accepted Answer

$$6.0$$ revolutions

Question 8

A mobile is shown in the figure. The horizontal support has negligible mass. Assume that all the numbers given in the figure are accurate to two significant figures. What mass $$M is $$required to balance the mobile?

Accepted Answer

$$3.6\ \mathrm{kg}$$

Question 9

A force of $$12.0\ \mathrm{N} is $$applied tangentially to a wheel of radius $$0.50\ \mathrm{m}$$ and causes an angular acceleration of $$1.50\ \mathrm{$$rad/s^2$$}. $$What is the moment of inertia of the wheel?

Accepted Answer

$$4\ \mathrm{kg\cdot m^2$}$$

Question 10

What is the gravitational force acting on a $$50\ \mathrm{kg}$$ person due to another $$50\ \mathrm{kg}$$ person standing $$5.0\ \mathrm{m}$$ away?

Accepted Answer

$$6.67 	imes 10$$^{-8}$$\ \mathrm{N}$$

Question 11

The mass of the Moon is $$7.4 	imes 10$$^{22}$$\ \mathrm{kg}$$, its radius is $$1.74 	imes 10^6$\ \mathrm{m}$$, and it has no atmosphere. What is the acceleration due to gravity on the surface of the Moon?

Accepted Answer

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

Question 12

A satellite of Jupiter has an orbital radius of $$1.34 	imes 10^9$\ \mathrm{m}$$ and a mass of $$1.89 	imes 10$$^{23}$$\ \mathrm{kg}. $$What is the period of Jupiter's satellite?

Accepted Answer

$$3.55$$ days

Question 13

A planet has an airless moon that is $$2.0 	imes 10^4$\ \mathrm{m} in $$diameter. Experiments reveal that a freely falling object near the moon's surface accelerates at $$5.0\ \mathrm{m/s^2$}. $$What is the mass of the moon?

Accepted Answer

$$8.75 	imes 10$$^{18}$$\ \mathrm{kg}$$

Question 14

The coefficient of linear expansion for lead is $$29 	imes 10$$^{-6}$$\ \mathrm{K}^{-1}. $$What is its coefficient of volume expansion?

Accepted Answer

$$87 	imes 10$$^{-6}$$\ \mathrm{K}^{-1}$$

Question 15

How much heat is required to raise the temperature of a $$300\ \mathrm{g}$$ lead ball from $$10.0^{\circ}$$\mathrm{C}$$ to 30.0$$^{\circ}$$\mathrm{C} if $$the specific heat of lead is $$128\ \mathrm{J/kg\cdot K}$$?

Accepted Answer

$$384\ \mathrm{J}$$

Question 16

A solid concrete wall has dimensions $$2.0\ \mathrm{m} 	imes 2.0\ \mathrm{m}$$ and is $$0.20\ \mathrm{m}$$ thick. The thermal conductivity of concrete is $$1.0\ \mathrm{W/m\cdot K}. If $$the temperature difference between the inside and outside surfaces is $$35^{\circ}$$\mathrm{C}$$, how much heat flows by conduction in 1 hour?

Accepted Answer

$$1.4\ \mathrm{MJ}$$

Question 17

What is the power that a person with surface area $$1.20\ \mathrm{m^2$}$$ radiates if his emissivity is $$0.895$$, his skin temperature is $$300\ \mathrm{K}$$, and he is in a room that is at a temperature of $$290\ \mathrm{K}$$?

Accepted Answer

$$62.6\ \mathrm{W}$$

Physics Study Notes: Key Concepts and Problems from Mechanics and Thermodynamics

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