skill22586

A box of mass 8 kg slides across a frictionless surface at an initial speed 1.5 m/s into a relaxed spring of spring constant 69 N/m.

How long is the box in contact with the spring before it bounces off in the opposite direction?

I was told to use this equation ...

1/2(m)(v^2)=1/2(k)(x^2) and solve for x

9=34.5(x^2)

sq.rt. .2609=x

=.519

This answer (.519) is not working.

Any ideas on what I'm doing wrong, or was i just told wrong?

A motorist driving a 1100-kg car on level ground accelerates from 20.0 m/s to 30.0 m/s in a time of 6 s. Neglecting friction and air resistance, determine the average mechanical power in watts the engine must supply during this time interval.

? kW

The driver of an empty speeding truck slams on the brakes and skids to a stop in a distance Dm = 254.84 m. The truck's initial velocity is v0 = 50 m/s and its total mass is m = 3137.8 kg. The coefficient of kinetic friction between the tires and the road is mk = 0.5

If the truck were carrying an amount of cargo that doubled its total mass, what would its stopping distance have been? (Assume the road is straight and horizontal).

D2m = ? (m)

A group of students observes that a wooden block of mass 0.67 kg on a string makes 15 rotations in 13.2 seconds at a radius of 0.70 meters.

The block's tangential velocity is = (m/s)

The block's angular velocity is = (rad/s)

Using the same data as for Question 1, calculate the centripetal acceleration and the centripetal force acting on that wooden block. Recall that the block's mass is 0.67 kg, with radius 0.70 m, and the block makes 15 rotations in 13.2s.

The blocks centripetal acceleration is = (ms^2)

The blocks centripetal force is = (N)

Thanks in advance for any explanation and answers!