Question

For the same force, why does a long cannon impart more speed to a cannonball than a short cannon?

The kinetic energy of an object of mass 2 kg is 16 J. What is its linear momentum?

A 70.0 kg archer, standing on frictionless ice, shoots an 80.0 g arrow at a speed of 80 m/s. What is the recoil speed of the archer?

Explain two ways by which you can increase the impulse.

Answer #1

Answer-1 In long cannon, the cannonball will receive more momentum due to force acting for more time in the long cannon.So for the same force, long cannon impart more speed than the short cannon to a cannonball.

Answer-2 Since kinetic energy is given,K.E=16 ,we know kinetic energy is given by K.E=1/2mv.v, also mass is given,M=2kg.so 16=1/2*mass*velocity*velocity 32=2kg*velocity*velocity so velocity=4 now linear momentum is given by=mass*velocity.SO Momentum=2*4=8(kg⋅m/s).

Answer-3 Momentum is coserved here due to frictionless ice.M1V1 + m1v1 = M2V2 + m2v2

Since before the archer shoots the arrow, the arrow and the
archer weren't moving so V1 and v1 are zero.

0 = M2V2 + m2v2.

M2V2 = -m2v2

V2 = -m2/M2 * v2

V2=- 0.08/70*80=0.09m/s

so recoil speed of archer is -0.09m/s.

Answer-4 two ways to increase the impulse. 1)Increase the force and 2)Increase the time interval.

1. Dan is gliding on his skateboard at 2.66 m/s . He
suddenly jumps backward off the skateboard, kicking the skateboard
forward at 6.52 m/s (as measured by an observer on the ground).
Dan's mass is 50.1 kg and the skateboard's mass is 7.09
kg.
a) How fast is Dan going as his feet hit the ground?
b) If the jump requires 9.20×10−2 ss to complete,
what average force did Dan exert on the skateboard? Include the
direction of the...

Question 1 (1 point)
Which is not necessary in order to do work on an object (use the
scientific definition of work)?
Question 1 options:
There must be a change in momentum.
A net force must be applied to the object.
The object must undergo a displacement.
A component of the force must be in the direction of motion.
Question 2 (1 point)
The change in gravitational potential energy for a 1.9 kg box
lifted 2.2 m is:
Question 2...

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