Q: A horizontal force $$F$$ acts on a block of mass $$m$$ sliding down a frictionless incline of length $$L at $$angle $$\theta. $$What is the final speed $$v_f of $$the block at the bottom?

$$v_f = \sqrt{2gL\sin\theta - \frac{2F L \cos\theta}{m}}$$

Question 1

A block of mass $$m$$ slides on a frictionless horizontal surface and compresses a spring with spring constant $$k by a $$distance $$x. If $$the block was initially moving at speed $$v_0$$, what is the maximum compression $$x_{max} of $$the spring?

Accepted Answer

$$x_{max} = \sqrt{\frac{mv_0$^2}{k}}$$

Question 2

A 2 kg block slides across a rough surface with a coefficient of kinetic friction $$\mu_k = 0.2$$ for a distance of 5 m before coming to rest. What is the work done by friction?

Accepted Answer

$$-19.6 J$$

Question 3

A spring with spring constant $$k = 500 N/m is $$compressed by 0.2 m. What is the potential energy stored in the spring?

Accepted Answer

$$10 J$$

Question 4

A 1 kg ball is dropped from a height of 5 m. What is its speed just before hitting the ground? (Assume $$g = 9.8 m/s$^2)$$

Accepted Answer

$$9.9 m/s$$

Question 5

A 3 kg object is pushed up a frictionless incline of length 4 m at an angle of $$30^\circ to $$the horizontal. What is the work done by gravity?

Accepted Answer

$$-58.8 J$$

Question 6

A 5 kg block slides down a 2 m long slide inclined at $$45^\circ to $$the horizontal. What is its speed at the bottom, neglecting friction?

Accepted Answer

$$6.26 m/s$$

Question 7

A horizontal force $$F$$ acts on a block of mass $$m$$ sliding down a frictionless incline of length $$L at $$angle $$	heta. $$What is the final speed $$v_f of $$the block at the bottom?

Accepted Answer

$$v_f = \sqrt{2gL\sin	heta - \frac{2F L \cos	heta}{m}}$$

Question 8

A 1000 kg car moving at 20 m/s collides with a stationary 4000 kg truck. After the collision, the car moves at 10 m/s at $$45^\circ to $$its original direction. What is the magnitude of the truck's velocity after the collision?

Accepted Answer

$$5.7 m/s$$

Question 9

A ball of mass 0.5 kg is hit so that its velocity changes from 2 m/s to 8 m/s over 0.3 s. What is the average force exerted on the ball?

Accepted Answer

$$10 N$$

Question 10

Which of the following statements about work and energy is TRUE?

Accepted Answer

Work done by gravity is zero if displacement is perpendicular to gravity.

Question 11

A projectile is launched with total energy $$E = 5 J. At a $$certain point, its kinetic energy is 4 J. What is its potential energy at that point?

Accepted Answer

$$1 J$$

Question 12

A 15 kg child slides down a slide of length 3 m inclined at $$30^\circ to $$the horizontal. What is the final speed at the bottom, neglecting friction?

Accepted Answer

$$6.7 m/s$$

Question 13

A 10 kg box is pulled 5 m across a horizontal floor by a force of 30 N at $$30^\circ$$ above the horizontal. What is the work done by the force?

Accepted Answer

$$75 J$$

Question 14

A 2 kg object is dropped from rest from a height of 10 m. What is its kinetic energy just before hitting the ground?

Accepted Answer

$$98 J$$

Question 15

A spring with $$k = 100 N/m is $$stretched by 0.5 m. What is the force exerted by the spring?

Accepted Answer

$$50 N$

Question 16

A 1 kg ball is thrown vertically upward with an initial speed of 10 m/s. What is its maximum height?

Accepted Answer

$$5.1 m$$

Question 17

A 2 kg block is attached to a spring and oscillates with amplitude 0.3 m and spring constant $$k = 200 N/m. $$What is its maximum speed?

Accepted Answer

$$4.24 m/s$$

Question 18

A 0.5 kg ball moving at 4 m/s collides elastically with a stationary 0.5 kg ball. What is the velocity of the first ball after the collision?

Accepted Answer

$$0 m/s$$

Question 19

A 3 kg block is pulled at constant speed across a rough surface by a force of 15 N. If the coefficient of kinetic friction is $$\mu_k = 0.5$$, what is the work done by friction over 4 m?

Accepted Answer

$$-60 J$$

Work, Energy, and Momentum in Classical Mechanics

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드