7. A girl standing 5.7 m from a high wall throws a ball with initial speed 12 m/

Question

7. A girl standing 5.7 m from a high wall throws a ball with initial speed 12 m/s, angled 36oabove the horizontal towards the wall. What is the time of the ball's flight from her hand until it hits the wall?

A. 0.48 s

B. 0.59 s

C.  1.7 s

D. 2.1 s

8. Suppose the maximum force you can apply to a wrench is 630 N. What is the minimum length wrench you will need to loosen a bolt which requires 120 N?m of torque?

A. 5.3 cm

B. 11 cm

C. 14 cm

D. 19 cm

11. Two carts travel along a horizontal, frictionless track as shown. The mass m cart traveling at speed 3v eventually catches up, collides with, and sticks to the mass 4m cart traveling at speed v. What is their speed after colliding and sticking together?

A. v

B. 2v

C. 4v/3

D. 7v/5

13.

A spinning wheel completes 4.5 rotations while slowing to a stop in 6.5 s with constant angular acceleration. What was the wheel's initial angular speed?

A. 1.4 rad/s

B. 4.3 rad/s

C.  8.7 rad/s

D.  13 rad/s

14.

As Keisha climbs several flights of stairs, what energy transformation is she making?

A. thermal energy into gravitational potential energy

B.  chemical energy into thermal energy

C.  chemical energy into gravitational potential energy

D.  thermal energy into kinetic energy

15.

Two spaceships have the same kinetic energy. Spaceship A has mass M and spaceship B has mass 4M. What is the ratio of their speeds, vA/vB?

A. 1/2

B. 1/4

C. 4/1

D. 2/1

Explanation / Answer

here,

7)

the horizontal distance , x = 5.7 m

intial speed , u = 12 m/s

theta = 36 degree

the time taken , t = x/(u * cos(theta))

t = 5.7 /( 12 * cos(36))

t = 0.59 s

the time taken is B) 0.59 s

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