Q: An astronaut lands on Planet X and measures its radius as $$3000\ \mathrm{km}$$ and the free-fall acceleration as $$4.0\ \mathrm{m/s^2$}. $$What is the mass of Planet X?

$$2.7 \times 10$$^{23}$$\ \mathrm{kg}$$

Q: A moon orbits a planet with period $$T = 10\ \mathrm{hr}$$ and the planet’s mass is $$3.0 \times 10$$^{23}$$\ \mathrm{kg}. $$What is the orbital speed of the moon?

$$9.7 \times 10^5$\ \mathrm{m/s}$$

Question 1

A block of mass $$m = 4.0\ \mathrm{kg} is $$pushed up a ramp inclined at $$	heta = 30^\circ$$ above the horizontal by a force $$F = 50\ \mathrm{N}. $$The coefficient of kinetic friction is $$\mu_k = 0.3. $$What is the acceleration of the block up the ramp? Use $$g = 9.8\ \mathrm{m/s^2$}.$$

Accepted Answer

$$1.4\ \mathrm{m/s^2$}$$

Question 2

In the setup above, if static friction is preventing the block from sliding, what is the magnitude of the static friction force required to keep the block stationary?

Accepted Answer

$$30\ \mathrm{N}$$

Question 3

For the same ramp and block, what is the minimum coefficient of static friction $$\mu_s$$ that will keep the block from sliding?

Accepted Answer

$$0.46$$

Question 4

Two blocks of mass $$m = 10\ \mathrm{kg}$$ are connected by a spring with spring constant $$k = 400\ \mathrm{N/m}. $$The spring is compressed by $$20\ \mathrm{cm}$$ and released. What is the magnitude of the acceleration of either block just after release?

Accepted Answer

$$4.0\ \mathrm{m/s^2$}$$

Question 5

A block of mass $$2.0\ \mathrm{kg} is $$placed on a ramp inclined at $$	heta = 53.1^\circ$$ with a coefficient of static friction $$\mu_s = 0.5. $$When released from rest, what will happen to the block?

Accepted Answer

It will remain stationary

Question 6

A ball is attached to a light string and swung in a vertical circle at constant speed. At which position is the tension in the string greatest?

Accepted Answer

Bottom of the circle

Question 7

A $$2.00\ \mathrm{kg}$$ ball is attached to a $$1.00\ \mathrm{m}$$ string and swung in a vertical circle at $$5.00\ \mathrm{m/s}. $$What is the tension in the string when it is parallel to the ground?

Accepted Answer

$$25.0\ \mathrm{N}$$

Question 8

A car drives at constant speed over a semicircular hill with radius $$R = 100\ \mathrm{m}. $$What is the fastest speed the car can have without losing contact with the road?

Accepted Answer

$$23.4\ \mathrm{m/s}$$

Question 9

A conical pendulum has mass $$m = 0.5\ \mathrm{kg}$$, length $$L = 2.5\ \mathrm{m}$$, and makes an angle $$	heta = 20^\circ$$ with the vertical. What is the period of the pendulum’s motion?

Accepted Answer

$$6.4\ \mathrm{s}$$

Question 10

An astronaut lands on Planet X and measures its radius as $$3000\ \mathrm{km}$$ and the free-fall acceleration as $$4.0\ \mathrm{m/s^2$}. $$What is the mass of Planet X?

Accepted Answer

$$2.7 	imes 10$$^{23}$$\ \mathrm{kg}$$

Question 11

A moon orbits a planet with period $$T = 10\ \mathrm{hr}$$ and the planet’s mass is $$3.0 	imes 10$$^{23}$$\ \mathrm{kg}. $$What is the orbital speed of the moon?

Accepted Answer

$$9.7 	imes 10^5$\ \mathrm{m/s}$$

Question 12

Two balls are dropped from height $$H. $$Ball A is dropped from rest, Ball B is given an initial horizontal velocity $$v_x. $$Which statement is true about their final speeds?

Accepted Answer

$$v_A = v_B$$

Question 13

A $$4.0\ \mathrm{kg}$$ block slides down a $$1.5\ \mathrm{m}$$ ramp at $$60^\circ$$ with $$\mu_k = 0.2. $$How much work is done by friction?

Accepted Answer

$$-5.9\ \mathrm{N}$$

Question 14

In the setup above, what is the net work done on the block?

Accepted Answer

$$28.1\ \mathrm{N}$$

Question 15

In the setup above, if the block starts at point A with speed $$2.0\ \mathrm{m/s}$$, what is its speed at point B?

Accepted Answer

$$3.4\ \mathrm{m/s}$$

Question 16

A $$5.0\ \mathrm{kg}$$ ball is shot horizontally from a spring-loaded cannon $$2.0\ \mathrm{m}$$ above the ground. The spring constant is $$k = 500\ \mathrm{N/m}$$ and is compressed $$20\ \mathrm{cm}. $$What is the speed of the ball just before it hits the ground?

Accepted Answer

$$9.1\ \mathrm{m/s}$$

Question 17

A football is kicked from the ground at $$15\ \mathrm{m/s} at$$ $$60^\circ$$ above the horizontal. How fast is the football moving at its maximum height?

Accepted Answer

$$8.1\ \mathrm{m/s}$$

Question 18

A $$2.0\ \mathrm{kg}$$ block is moved from rest by a compressed spring ($$k = 800\ \mathrm{N/m}). It $$travels over a floor with $$\mu_k = 0.3$$ and stops after $$D = 6.0\ \mathrm{m}. By $$how much was the spring initially compressed?

Accepted Answer

$$0.39\ \mathrm{m}$$

Question 19

Two balls of different masses reach the same height when shot into the air from the ground (neglect air resistance). Which statement must be true?

Accepted Answer

Both balls left the ground with the same speed

Question 20

An electric scooter’s engine produces $$4.32 	imes 10^6$\ \mathrm{J} of $$energy in one hour. What is the power output of the engine?

Accepted Answer

$$400\ \mathrm{W}$$

PHYS 201 Exam 2 – Step-by-Step Physics Guidance (Chapters 5–7)

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