Question

1) It is friction that provides the force for a car to accelerate, so for high-performance cars the factor that limits acceleration isn't the engine; it's the tires. Part A For typical rubber-on-concrete friction, what is the shortest time in which a car could accelerate from 0 to 70 mph? Suppose that ?s=1.00, ?k=0.80, and ?r=0.02.

2.) The forces in (Figure 1) are acting on a 1.0 kg object. What is

ax, the x-component of the object's acceleration?

3.)A crate pushed along the floor with velocity v? islides a distance d after the pushing force is removed.

Part A If the mass of the crate is doubled but the initial velocity is not changed, what distance does the crate slide before stopping? Express your answer in terms of d

Part B If the initial velocity of the crate is doubled to 2v? i but the mass is not changed, what distance does the crate slide before stopping?

Express your answer in terms of d.

Answer 1

Answer 1

Answer 2

2 m/s^2

Answer 2

max accelration can get a =0.8*9.8
70 mph = 31.292 m/s

time taken = 31.292/(0.8*9.8) = 3.99 sec

2) no figure

3)
a)energy conservation
0.5*m*v*v = u*m*g*d

0.5*(2m)*v*v = u*2m*g*D
Dnew = d

b)
0.5*m*2v*2v = 0.5*m*D
D= 4d